Since there's little to zero information about Rune as a game on any deeper level, I decided to write a bit of details in an orderly manner about the game, purely out of fun times and appreciation.

First off, adressing a very common question.
'How is this game an action game? I'm stuck in a barren cave!'

The game starts out being almost purely a platformer and puzzle solver type of genre. There's little to do except exploring all the nooks, and once in a while, you are rewarded with boring lizards or a shield, but generally the action is very meager and the experience is.. something that I would wager have left many, many players stop playing all together.
About 1/5th the way through the game, the game starts to become more action oriented. You meet more enemies in general, and you start getting some satisfying encounters frequently. The puzzle and exploring elements are still going to be present, and those will persist throughout the whole game, although the game does become slightly more linear towards the end, but emphasis is still on 'Slightly'.
For the very casual gamer, many of the puzzles can seem almost unfair and can leave you scratching your head and frustrated for quite a while. It is a central part of the games progression that you must find that obscure road ahead to the next area, and with how little information there is about the game online, understandably, some might completely get stuck in certain areas. My tip to you is this - Scan the entire area completely and try swinging on anything tangible. There is always a way forward. It is very rare that you have to backtrack, but it happens atleast once in the game, so check there, too.

Now here's some random trivia about the monsters that you might want to know. It's completely random, and they're listed roughly in the order of which you're going to meet them, so here goes..

1. Your mentor. The very first battle in the game is against your old teacher. He acts basically like a clone of you, just reskinned and with AI controlled. Not much can really be said about the guy, as the fight is straightforward. Weave and swing at him with any weapon. On Hard, you might find it useful to throw your weapons repeatedly in his face with the Q key to whittle him down safely, but his AI is pretty slow, even on hard. He takes roughly 28-30 hits to down on HARD, which is a lot.

2. Cave Crabs. It has a very tight aggro zone, and generally just wants to be left alone, unless u disturb them. They are sluggish at start, but weave pretty quickly while they swing at your feet in a super tight arc. If they hit they hit for surprisingly high damage on Hard, just one hit can take nearly a full health bar away. You can easily submit a crab by just jumping on top of one, as the hitbox is too tight and low to hit you. You can chop these up fast with downwards axe and mace chops, 3 hits of a tier 1 weap will do on Hard, and just 1-2 on easy.

3. Snake Vases. Immobile, and a nuisance more than a threat. Standing close to these will have them lash out at you in a predictable pattern. Stand too close, and they will hit you for some minor damage. The trick to killing these is to stand just outside their hitbox area, and then swing your tier 1 sword exactly when the tongue of the creature reaches close to you. With some practice, this foe becomes a non-threat. Be careful though, as these creatures can snatch and grab your weapon right out of your hand if the angles of the impact area between your weapon and the tongue is just right. They take only 1 swing to kill on any difficulty, but be aware that the vase-shaped body is entirely invulnerable.

4. Giant cave crab. These are the size of a bear, and they're very territorial. They have a defensive orientation, and prefers to wait until you get into closer range for attacks. Their hitbox is proportionally larger and they have the ability to power up a strong power attack that is very easy to dodge, but if you do not, you're going to lose easily half your MAX hp bar right there on HARD. If you hit them at all with anything while it's stalling, it will flip on its back and be defenseless and ready for slaughter. However, they can recover if you do not deal some damage to them while they're down, in time. They can take a surprising amount of punishment, easily more than 15 swings of a tier 1 weapon, but the front limbs and legs are easy to serve with axes and swords, which leaves them crippled. If you manage to serve both front claws quick, the crab will retreat inside its shell and bleed to death.
You can jump on top of these crabs where they can't hit you, but this should trigger their stall ability which will fling you off.

5. Goblins. Small and barely intelligent enough to wield a weapon, they have literally only one type of attack. A straight chop downward, with fairly short range. They're able to jump and run around quiet well, and are relentlessly aggressive in their pursuits - not shy to swing weapons mid jump. They lose all courage and flee if you manage to chop a limb clean off. On HARD they can actually sometimes keep up with your movements and sidestepping and still hit you on retreats, especially if they're armed. There's 3 types of goblins - An unarmed goblin, the armed goblins and the chieftains. Goblins are usually armed with bone clubs and stone axes, with or without shields, and chieftains are basically just larger, beefier goblins with red mohawks. Goblins have lowish health, a good 6-8 swings of a tier 1 weapon should in most cases kill one outright on HARD, but Chieftains are tougher.

6. Zombies. They're the unworthy vikings that didn't make it to Valhalla, and thus have been banished to Hel - the realm of Loki's' daughter. They're only killable if you chop their head right off clean, or else they will just keep reviving again and again. This is easiest to do with swords, and specifically the roman swords very first still stand swing, is designed perfectly to decapitate a zombie the moment they revive. Practice your positioning for a while, and you will soon master the neck slicing skill. Another way to dispose of zombies is to whack them with a lit torch or rune powered hand axe or roman sword - this will burn them up in the matter of roughly 5 seconds.
Zombies move fairly slow, but are aggressive. They are predictable, and rarely jump, although they can do a forward lunge type of punch. They do light damage, but have a special ability to release a column of green gas in your face that travels briefly forward for some seconds. This gas does some good damage on HARD and can quickly take more than 1 bar of health. As a finale note, you're going to be facing a lot of these in Hel, and there's no shame in simply ignoring them when you can

7. Skeletons (Modded into later releases). Acts exactly like your mentor in the absolute beginning of the game. No jumping, just weaving and dodging and swinging. They're frail and die in roughly 8 hits of a tier 1 weapon on Hard. They carry tier 1 swords and axes and later can be found with roman swords. Also carries a shield. These opponents are the first real threat you face, as they have comparable range of hit to Ragnars'. Can potentially kill you quick, as you sometimes fight upto 3 of them at the same time.

8. Helhounds (Modded into later releases). A reskinned, resized and complete makeover of a Wendol. Has the same AI as a Wendol, which also means they do not move well in tight corridors - their AI is not really compatible with that setting. Normal swings deal moderate damage and light you on fire for extra damage. The real pain in the ass is their lunging move, which they do constantly if you stand outside their narrow'ish hitbox. Hard to really dodge and takes easily 1/4 your MAX hp on Hard straight off. Has good health as well, easily taking 10-12 tier 1 weapon swings to kill on hard. You can jump over these puppies, but it is not advised as their lunge will hit you mid air.

9. Vikings. You're going to be beating on these bad mouth, bitch bred guys a lot when you enter the city of Thorstad. They act much like your old mentor, but have improved AI, especially on HARD, and they are less shy about coming to the offensive. Perhaps the biggest difference between these guys and the skeletons and mentor, is their improved armory to compliment the AI - they carry a lot of tier 3 weapons, and they also come in a few varieties. Basically, normal vikings, berserkers and elite troops. The Berserkers are distinct by their horned helmets and very aggressive AI. They are also faster than Ragnar on foot on HARD, and they never carry shields. Instead, they have more HP than normal vikings, and they also deal slightly more damage with the same weapons. Vikings are already capable of slicing Ragnar to bits in 3 combos, but Berserkers can sometimes deal 100% of your HP bar in dmg in just 2 volleys of 2 hits, so you better be dodging those blows on HARD. Elite troops are vikings clad in heavy armor, heavy shields and broadswords, and they're beefier, but arguably not as dangerous as Berserkers. Vikings can take quite a beating on HARD, easily taking upwards of 15 swings of tier 1 weaponry or 7-9 of tier 3.

10. Giants. (Modded into later releases) These are huge, relentless and unfair enemies in every sense of the word. They were never balanced properly for the game, and luckily you only encounter around 10 of them in the entire game, all of them you can cheese or run away from. They're twice Ragnar's size and have enormous hit boxes, easily able to chop you up from afar. They carry either viking war axes or Sigurd axes, and they swing these really fast, with really short cooldown, and they hit really hard. 3 hits of a charging Giant can kill you on Hard.
The only reason the giants are killable is because they can be cheesed by strafing and exploiting their unrealistically tight 'swing zone' (the zone of distance from Ragnar to opponent before they start swinging). In other words, even if it looks like they can easily reach you (they can) they might not swing their weapon, which is lucky for you. They have massive health on HARD, easily taking your puny tier 1 swings forever at 25+ swings. Even strong tier 3 swings, you need at least 12. They often come in pairs.

11. Wendol. These look like a mix of a great ape and a bear, on steroids, and they act kind of like how you would expect a charging bear would - by lunging and swinging at you relentlessly. They come in differing sizes throughout the game, and range from the size of a polar bear to that of a full grown elephant, obviously having more health and mauling power the larger they are. A few of them even have their own theme song playing when you encounter them, which adds greatly to their fear factor. The helhounds share most of the AI of these beasts. They're straight forward, but the best way to kill them is to circle strafe around them while you hug them close - the monster can only turn so fast, and you will be able to escape much damage this way.
They deal roughly the same damage as the helhounds, except possibly slightly more, but it is not excessive. Their danger comes mainly from a huge hit box on their lunge attack and their massive health, easily taking upwards of 25-40 hits of a tier 1 weapon, depending on whether it's a small or giant version. Even with tier 3 weapons, you're going to have to swing something like 15-20 times before they collapse. Finally, you can literally run away from all of them, so you do not always have to take up a fight with them, which is good to know.

13. Dwarfs. These creatures look more like short trolls, but they're deadly. Their AI is complex compared to other humanoids, being both good at attack and defense. They're able to actually use the shield to block attacks. Additionally, dwarfs are just as adept at lunging attacks as the Wendol and Helhound, doing a good 1,5 bars of damage on HARD and sending you flying for a ridiculous distance, regardless of what weapon they apply.
Dwarfs have the additional ability to randomly throw their weapon at you, dealing upwards of 4 bars of damage, which is close to half your total HP! They will then charge you down or pick up their weapon again,

They are not entirely predictable, yet they do always follow up a shield block with a lunge. Dwarfs do not attack with a flurry of blows, but their single strikes can smash you in 3-4 hits on HARD. Dwarfs are also superior at teaming up in numbers of 2-5+ , and together with their wide array of weaving skills, they can surround you easily.
In short, these bastards are fairly fast, and intelligent. Dwarfs come in 2 variations, workers and warriors - The workers are clad in leather and often wear lesser shields and tier 3 or 4 weapons (In a single arm, mind you). The warriors are distinct by carrying black-ish armor, massive shields and rarely anything but tier 4 weapons. They're also slightly beefier.

Dwarfs have one large flaw. They're prone to falling over by getting hit by maces, and this can lead to some easy kills where you can smash helpless dwarfs to bits. The mechanic is much the same as with the giant cave crab.

Now, I am not sure of this, but dwarves seem to especially resistant to sword attacks, and not happy getting mace struck.
Dwarfs take more punishment than vikings in general, so at least 18+ tier 1 weapon swings, but realistically you're going to be hitting the shields a lot. Usually, 4-5 hits of a tier 4 Dwarven worker hammer will kill a worker on HARD, perhaps 1-2 more hits for a warrior.

14. Sentry bots. These stalk the dwarf fortress, in crevasses and sewer systems especially. They are tiny but come in packs, and on HARD they're absolutely to be taken serious. These 2 versions. One unfolds blades when it gets close, and start jumping up and down while pursuing you, attempting to slice your head off. 4-5 hits with a tier 3 weapon can smash these up, but you need to time your attack to hit them safely due to their tiny size and erratic movement. The other version unfolds in front of you as well, but you will immediately notice that they start glowing red before they begin firing a volley of fireballs your way. This stuff hurts and sets you on fire, but the range is limited and the ball are easy to dodge if you take distance and is not confined to a narrow space. After they stop their barrage, which takes roughly 3 seconds, they burn up and break down themselves.

15. Dwarf terminators. You meet like 4 of these in the game, and are some of the most sluggish enemies you'll encounter in terms of AI response to Ragnars movement. They are also slow and turn slowly. This makes them laughably easy to defeat if you are used to HARD mode humanoids, despite all their health and weaponry. That said, they can slice you like a pizza in 3 seconds flat if you let them. They employ a simple pursue and attack plan, aggressive and to the point. Their melee attack takes a few moments to charge up, and then they attack you by standing still and spinning their clawed arms in a circular motion. If you crouch, this won't even hit you, and you can whack at his legs. If you stay crouched, however, he will lower himself and start the same movement, sweeping the floor with your ass if didn't move out of the way in time. If you create distance between you and him, he might start charging up his fireball cannons at you, which takes like 3 seconds of animation to even begin. When he does begin firing balls of flame at you, though, he will continue relentlessly. 4-5 volleys is enough to terminate your full-health Ragnar on HARD, but the balls move slow enough that you can dodge if you keep a fair distance. These terminators take just about as much punishment as a great sized Wendol, but because they're relatively easy to whack at, they fall sooner than you might think.

16. Sarks. What happens when you cross the zombies of Hels' region with the blood of Loki? You get these super powerful monstrosities. Vaguely humanoid, these creatures are on the same level as the Giants in terms of strategy on how to beat them, as these too share a fairly narrow swing zone. This is pretty much their only saving grace, for where you can run from giants, you're required to kill these in relatively confined areas, and because of that you're almost expected to kill them with cheese if you're playing MEDIUM or HARD, without suffering death in 2, maybe 3 hits, if you're lucky. They have one additional ability that Giants don't have - they can do a perfect somersault. This jump is an animation that takes some time and leaves them vulnerable to a counter attack for a brief moment as they land and taunt you. When they jump is pretty random, but there needs to be ample vertical space. These super zombies come in 4 varieties. Unarmed, Battle Hammer, Battle Sword and Battle Axe. All tier 5 weapons. Their size and their weapons easily gives them the widest and most unfair hitbox in the game, toppling even the Giant. A general rule of thumb is, that if they ever swing, you probably are getting sliced, unless you were really lucky with a counter attack or strafe in the last moment. Also, don't even think for a moment that the unarmed version is any less deadly. They might have slightly less effective range, but they can smash your 100% healthy head in with 2 quick combos of their fists.
In terms of health, these monstrosities vary somewhat. Sword variation is less armored with less health, Axe is beefier and Mace is beefiest. They take easily 15-22 hits of tier 3 weaponry, and a ridiculous amount of tier 1 swings - sometimes up to 60 hits from tier 1 sword and 'only' around 30 from tier 1 mace. It takes roughly 8-11 swings with a tier 5 weapons to take an armed one out, depending on weapon type used.

Now I want to write a bit about hazards in the game.

There's fire, water, green shrooms, jellyfish, anglerfish, steam, lava, sludge pits, traps and obviously the 'bottomless' pits. These pretty much cover all the hazards, if I'm not forgetting something.

Fire: Not all fires light you up, this means torches and other cosmetic fire effects do not necessarily hurt, but those who do are usually fairly obvious. Getting touched by fire does some small damage, about 1 bar on HARD, and then sets you burning for minor DoT that ticks like 5 times. Some fires that are especially intense will almost instantly wreck you. Jumping in water WILL remove the remaining DoT. All foes you meet can be lit on fire from all the same sources Ragnar can. Zombies are especially vulnerable to fire.

water: Ragnar is an excellent swimmer and can hold his breath for like a full minute before he start drowning. Drowning does periodic damage in ticks each 3 seconds or so, roughly 1 bar of damage. Nearly all foes in the game are immobilized if they're tossed in water or jump into it by accident, and it does not take long at all before they drown and die. This is especially something you can trick Dwarfs to do, in the early parts of their region.

Green Shrooms: They emit a sickly Neon-green color. If Ragnar bumps into these, they release a small immobile gas cloud that can hurt Ragnar for continuous light damage.

Jellyfish: They look pretty much like decorations, but these things actually do tiny damage to Ragnar if he chooses to embrace the swarms up close. It's an incredible detail, if you ask me.

Anglerfish: You meet 2 of these in the game, and they're big enough to swallow you whole. Technically, they could be considered actual foes because they have some AI, and will vaguely pursue Ragnar with their limited movements. They're invulnerable, fast, but very clumsy at turning. If you're moving at all in the water, they're very unlikely to ever get you; but if you deliberately try to swim straight at them, they will line up their big mouths on you and chomp you in 1 hit. Instant death. The animation is kinda wonky and delayed, so you can tell the developers didn't really spend too much time polishing this thing, but I still love the detail.

Steam: Usually comes from machinery or from the ground in areas of volcanic activity. It works a bit like fire, except you don't get a DoT, and most steams can rip you to shreds in 1-2 seconds. Foes also get wrecked if they touch this stuff.

Lava: Hurts like fire if you grace it with your foot, but if the game detects Ragnar swimming in lava, he'll get instantly barbecued in 1-2 ticks. Any touching of lava also gives the fire DoT. Lava obviously also turn your foes to crisps.

Sludge Pits: Green sludge. Not much to say except don't swim in it or touch it. Deals periodic damage ticks to Ragnar, which is comparable to fire damage. Zombies and Sarks are immune to sludge effects. Ragnar will start drowning instantly aswell if you submerge into it.

Traps: Rune is littered with traps, and these traps are both hidden and very obvious. There's the usual swinging blades and hooks that will instantly gib Ragnar, walls and stones that will smash you and projectiles being shot out at you, and much more. Foes can oftentimes be lured into traps and be killed this way.

Bottomless Pits: Characteristic by being a pit that is just colored black. You fall into one of these, and you'll die automatically. Enemies also die if they're tricked into these.

This section forward contains information about Runes' items. There are foods, torces and diffrent kinds of runestones.

FOOD (Health)

Ragnar eats food sources for instant health gains, and here's the following.

Lizards: These wiggling reptiles can be found all over the game, often in clusters of 2-4 in dark areas and in the open. They seem to come in 3 qualities, as there are lizards that heal roughly half an HP bar, a full HP bar and sometimes around 1,5 HP bars. They can alter slightly in their color palette, but this does'nt seem to correlate with the quality of lizard Ragnar eats. Lizards can hang on walls, be hidden under smashable objects, and they even have their own little audible slithering sound that can hint at their nearby location. Lizards that hang too high to be reached can be hit by Ragnars' weapons and fall to the ground immediately under.

Fruit: These hang usually on trees or branches, sometimes in cluster of 2 or more. There's small, green apple looking fruits and a richer purple colored variation. The green ones heal barely half an HP bar, and the purple ones heal a full HP bar.

Mead: Is basically a trunkard in game. Ragnar drinks these for a nice 1,5 HP bar health boost.

Leg of Meat: Is a valueable item in game. Comes in 2 versions: small and large hunch. Small ones heal 1 HP bar, and large ones heal 1,5 HP bar at least, but seems to sometimes heal up to 2 full bars.

Misc. item - the torch

The torch in Rune is a temporary weapon and light source. Torches can be found lit or unlit on the ground or on the walls, as part of decor. Some enemies also carry these when they're on scout or guard duty. Torches cannot be stored, and attempting to climb ropes will drop the torch on the floor. Torches can be thrown for minor damage or positional light source, but a thrown lit torch does not set enemies on fire.
Whacking enemies with a lit torch sets the enemy on fire for DoT. Whacking enemies with an unlit torch result in some really tiny damage and no flinching. Torches that are lit go out if you make contact with objects or enemies 2-3 times. Unlit torches can be reignited promptly by pressing use key near almost all decor fire sources or other lit torches. Torches yield much needed lighting in areas completely black, and they are useful as a weapon against the regular Zombies of Hel.

Rune Stones: There are 3 types of Runestones. Rune Power stones, Health Runes and Frenzy Runes. Runes are considered the greater rewards of Rune, and are often the reward for exploring secret areas and hard to reach places. They omit a humming noise that can tell you about their placement.

Rune Power stones emit yellow lights and come in 2 varieties - Lesser and Greater. The lesser runestoned fill up 1 Rune Power bar on your Rune Power meter, on the right of the HUD.

Greater Runestones fill your entire Rune Power bar up, and adds a filled bar to your maximum available ones. These are extremely rare.

Health Runes emit blue lights, and these are arguably the most valuable runes in Rune. They fill up your HP bar and add another filled HP bar to your maximum available ones. Since Ragnar starts out with 5 HP bars, finding these can really add necessary meat to sustain mid to late game punishment. In fact, without any health runes at all, you can be slaughtered in 1-2 hits by almost any opponent in the later game on HARD, so you can see why these are important.

Frenzy Runes emit red lights and these will fill up Ragnars' rage bar to the max and activate rage mode. Rage mode is going to be explained below. Often these are positioned in areas where bigger fights are going to take place.

In the following, I'll try to explain the frenzy bar and rune power.

On the very bottom of the HUD, there's a small, horizontal bar that becomes visible and fills up as you deal damage to enemies. This has to be actual damage, so you cannot fill it up by hitting walls, corpes or objects - you must deal damage directly to foes. The moment you stop dealing damage, this bar quickly deplete.
How quick it fills depends on difficulty. On Easy, it fills pretty quick, on Hard, you need to slaughter a small village of creatures in quick succesion to pull accumulate enough bloodlust to turn Frenzy. The bar fills in proportion to damage you deal, so it fills faster with tier 5 weapons than swings of tier 1 weapons.
Now, what is the Frenzy mode.
Turning Frenzy is a full mechanic by itself. First you'll note that Ragnar roars and shouts when taking damage and swinging weapons. His eyes also glow bright red. Then you notice that your bloodlust bar now has become very large on your HUD, and seems to deplete at a steady pace. This bar now also temporarily acts as a shield for damage taken, but damage taken will deplete chunks off of your remaining frenzy, and can be very quickly depleted if you're taking heavy hits. While under the frenzy effect, Ragnar moves slightly faster, does'nt flinch from counter attacks and he deals twice his normal damage to enemies. This means a frenzied Ragnar can slice up enemies in half the hits. When it has depleted, Ragnar returns to his normal state and is vulnerable to damage.

Rune Power is the yellow bar to the right on the HUD. It does'nt show up at all before you pick up your first Runepower stone. Rune power is used for one thing only, and that is to enchant your weapons temporarily with additional effects that vary completely depending on which of the 15 weapons in Rune you have equipped. All Rune enchantments dissipate immediately if you change weapon or throw it, so this is not adviseable. How long the duration of the effect is, depends somewhat on the weapon, but it can be as low as 10 seconds and as high as 15-20 seconds.

Here I'll try to tell everything to know about Shields in the game.

There are 6 shields in the game, and each shield has a durability bar that depletes with damage taken. Shields are all equipped in the off hand slot, which means you can never equip tier 4 or 5 weapons and shields at the same time. Your foes can equip everything with a shield, which is really unfair. Ragnar can pick up shields and replace shields with shields that have more durability remaining, even if it is a downgrade. So, if you carry a Goblin Shield and try to pick up a Dwarven metal shield with the same remaining durability, Ragnar will refuse to pick it up. A simple system that the developers did'nt really think through.

Goblin Shield: Really small shield that protects a small area in front. Almost useless against monsters, but is pretty useful to block straight chopping swings of weapons. Durability is roughly 40% out of the full bar. Even though it's the shittiest shield, it can still take atleast 3 swings of some pretty hefty weaponry before depleted.

Wooden Viking Shield: Small shield, but still like 1,5x larger than the Goblin shield. Is not as useless as the goblin shield in terms of coverage. A new shield can have upto 60% durability, and it can often take 4-5 heavy hits.

Metal Reinforced Round Shield: Exactly like the small shield, just reskinned. Despite being made of metal, it does not seem to have any advantage. It would not surprise me though, if it has some hidden resistance to slashing weapons.

Metal Viking Shield: Now we are talking. This shield is slightly wider than a round shield, and offers much more vertical protection in a triangular shape. It offers good coverage against all weapon swing from the front directly, and limited from the sides and at rest. This shield is thus also useful against monster type enemies. Has only 60% durability though.

Wooden Dwarf Shield: This is a great shield with great coverage all around, both vertically and horizontally. It has something like 80% durability. It offers good protection from the side aswell as full protection from the front. It is good against monster hits; and offers decent protection even at rest.

Metal Dwarf Shield: This is the best shield in the game. Only very slightly better coverage than the wooden shield, it looks more badass and has 100% durability. It offers the best protection in the game, and can really save you a lot of hits from all frontal attacks.

Using shields effectively is a lot about positioning. If the enemies are short and slash at your feet or legs, you're going to take damage regardless if you're actively blocking or not. By crouching and blocking at the same time, you can get almost 100% protection with the larger shields, even from the nibbling of cave crabs. Shields offer good resistance to the shield arm at rest, and the large shields can protect Ragnars left side quite well.

Shields are especially good at covering sword and axe swings, but maces, especially high tiers, seem to often bash right through.

So here is all I know about the weapon types.

There are 3 in the game. Swords, Axes and Maces.

Swords: In game description tell you 'Good against fast and unarmored units'.

Damage.
Swords of any tier deal less damage than other weapon types, how much less depends which type you compare to.. There are some speculations that certain armor clad units take even less damage specificly from swords, but I have not tested this yet. Swords are especially capable of arm and head severing.
Evidence: after testing swords on Sarks compared to maces and axes, I have found a pretty significant diffrence only from using tier 1 Viking Short Sword, which deals almost half the damage of a tier 1 mace on armored Sarks. The rest of the swords do not seem to deal excessively less damage compared to other tiers, so this is somewhat strange.
HitBox.
Swords tend to have the widest, thinnest and longest hitbox of all weapon types. Sword swings typical aim towards the center in a very wide arc. All this means swords are especially good at dealing hit and run damage with less chance of counter attack. Shields are especially effective against sword attacks, as they can generally take more hits from these than other weapon types, and have greater chance to cover the wide arcs of the swings.

Axes: In game decription tell you 'Good against lightly armored foes'

Damage.
Axes of any tier deal more damage than comparable tiers of swords, but slightly less so than maces. Axes are effective against nearly all foes. Axes can sever limbs, but it appears harder to do so due to axes hitbox mechanics.
HitBox.
Axes tend to have a thicker, shorter hixbox than swords. They are also not swung in as wide an arc in most cases. Axe swinging is a mix of quick attacks and controlled arcs, which make precision chops a possiblity, and hit and run against enemies with less range or equal to Ragnar, feels fairly safe. They're more risky to use against the more dangerous enemies though. Axes are better at splitting shields than swords for sure.

Maces: In game description tell you 'Good against heavily armored foes'

Damage.
Maces of any tier deal the most damage. Enough so that it takes noticeably more hits to kill the same opponent with an equal tier sword. Maces are especially effective against shields, sometimes seeming to bypass shields in scenarios where it would seem like a blocked attack. Maces are incapable of severing limbs.
HitBox.
Maces have the shortest, fattest hitbox in the game, especially the big hammers. The arc of swing is shorter than axes, except for the Tribal mace, and maces always swing in some type of smash motion. They're pretty good for all out pummeling due to having usually the highest DPS potential, but they're markedly worse than other weapons at hit and run attacks. Many maces swing slower than other weapons, and some are even slightly delayed. This means timing attacks can be a more difficult affair with hammers. Hammers are really risky to use against enemies with a lot of power, as you're going to be closer to their swingzone - if not directly in it. Maces are pretty damn effective against dwarfs and giant cave crabs though, and they have their effective use.

Remaining topics by order: Weapons in game, In depth Rune Powers and misc. hidden mechanics. There are also some bosses throughout the game, but that is more of a walk-through topic than an actual game mechanic one.

From here on out, I'm going to list and describe the 15 weapons of Rune and their Rune Powers.

Swords:

Tier 1 - Viking Short Sword.
First weapon you acquire, this weapon deals the lightest damage in the game. Its combos are quick, its reach is long and it attacks fast in long, horizontal sweeps. Can hit enemies standing slightly behind Ragnar.

Runepower: Lifestealing, cost 1 RP bar
This enchantment temporarily makes you steal life from enemies damaged by hits. The life stolen pr. hit is something like half an HP bar, but it is very much possible to steal life from several foes in the same sweep. A very useful ability to have when you're low on health and have an opponent ahead of you that can be managed somewhat safely. Hitting Zombies also steals life, so you can 'milk' life from zombies as much as you like (when they're still standing).

Tier 2 - Roman Sword.
This weapon is arguably the best tier 2 weapon out there. It seems to slightly stronger than a tier 2 weapon should be. Is very efficient at decapitating zombies as well as other humanoids. Hitbox is good and swings are a mix of cross chops and sweeps.

Runepower: Flameblade, cost 2 RP bars
Sets the sword on fire and makes each hit deal slightly more damage aswell as put enemies on fire. Is great for mowing down zombies, but you could just as well use the Hand Axe for this, at half the RP cost. Not really worth to use if you ask me.

Tier 3 - Viking Broard Sword.
This weapon has some of the longest sweeping strikes in game. It is balanced by having low damage for a tier 3, and having some pretty slow recharging, due to the sweeps being so damn long - making attacks relatively slow to pull. It is definately great at pot shots and can effecitvely slice limbs off of humanoids without shields.

Runepower: Ally, cost 2 RP bars
A very unique power that lasts long. Hitting opponents just once make them glow blue and either puts them in a trance or make them your temporary allies. The effect is longer than 30 seconds, so they stay your ally for a while. Hitting your allies does not turn them hostile, and neither does changing your weapon after you have turned them over. Your foes will respond to your new allies and attack them, aswell. Can really turn the tide of a large scale battle, and is a very useful ability for the cost of RP.

Tier 4 - Dwarven Work Sword.
This weapon is a twohander and a slightly longer range than the one handed swords. Swings a lot in X patterns. I personally really dislike this weapon, finding it very poor against dwarfs, due to being about as cumbersome as a hammer but with less damage and a poor performance against shields. It seems almost like an obsolete weapon, but this may be the fault of when you happen to get it, and the opponents you happen to meet onwards from there. This is one of my most biased descriptions, so take it for what it is.

Runepower: Lightning Bolts, cost 3 RP bars
This enchantment is powerful and to the point. Releases a small cloud at the beginning of each swing combo performed, which instantly saps nearby opponents for really heavy damage. Messes up most foes in the matter of a few seconds. Each cloud lasts for about 4 seconds, and the range of the bolts are atleast a few meters, so it is useful to release them from a safe distance and let the bolts go to work. Powerful and useful , even for its cost.

Tier 5 - Dwarven Battle Sword.
Can we take a moment and just appreciate how epic this sword looks? It swings significantly faster and with more precision than the work sword, and it has the longest Hitbox in the game. This one also swings in X patterns. Deals the least damage of all tier 5s though, but is powerful enough to slice up anything in game very quickly regardless.

Runepower: Avalanche, cost 5 RP bars.
The most devastating enchantment in the game by a long shot. Every initial combo swing releases a magical avalanche of boulders that fire straight out in front of you, covering a wide and deep area in front with relentless, instantly gibbing boulders. Everything gets destroyed, nothing is safe. The avalanche keeps firing for roughly 2-3 seconds after each swing. Extremely well worth the RP cost, if the opposition is of a serious enough threat.