There are 15 classes/professions in W8. Of these, 5 (the casters, Bishop, Priest, Alchemist, Psionic, and Mage), are not able to learn this skill.
This leaves 10 classes. Bard, Gadgeteer, Lord (even with the class bonus), Valkyrie, Ranger, Ninja, Monk, Samurai are only mediocre at close combat, and suffer heavy penalties for dual wielding.
This leaves only two classes that excel at dual wielding: The Fighter and Rogue (Berserking and Backstabbing). These are the only two classes that seem worth it, to work on Dual Weapons skill.

I disagree with this assessment.

Thing is, the strongest offhand weapon, by far, is the Diamond Eyes. Hence, for a class to be good at dual wielding at higher levels, the class *must* be able to equip this particular weapon. This rules out Rogues. Worth noting that Valkyries and Rangers can use this weapon, making them competent dual wielders later in the game.

Another thing is that, to my understanding, assuming you're actually dual wielding, the Dual Weapons skill is *more* important than the Close Combat skill. Hence, if you ignore Berserk, Lord > Fighter (and Berserk doesn't really matter unless you're comparing different classes; when looking at a way to build a Lord, dual wielding is definitely favorable).

Also, I would argue that the classes you mention, particularly the hybrids, are not "mediocre" at close combat; they're actually plenty good enough, to the point where having a few of them in the party is enough to make the party a melee damage party. The Fighter's Close Combat bonus, while nice, isn't as game-changing as you seem to think, especially since other skills are more important. A valkyrie, for example, gets a bigger boost from her class skill than a Fighter would, assuming Polearms are being used (which does preclude dual wielding, however).

Another thing to note: Priest and Bishop can't learn Dual Wielding, but if you class change into one of these classes, you don't lose the skill that you've already built up, and both classes can equip Diamond Eyes. This leads to one rather exotic set-up; Bishop with 1 Fighter level. Just take the time to build up Dual Weapons (possibly delaying the level up, and possibly using strategies that some players may not like for various reasons), and you can have a Bishop who can Dual Wield to some degree.

(Also note that dual wielding will still give you a second attack even without the skill; it might be an interesting strategy at some levels, even if you don't get the skill, and 1/3 of the possible skill increases will be wasted. Just don't do this once the Priest/Bishop is strong enough to get a second attack with only one weapon.)

Let us break it down:

Fighter: Berserk attack option, Stamina regeneration, KO on enemies, both in melee and ranged, Close Combat skill bonus. You definitely want to dual-wield with this class, using Sword and Mace and Flail skills (Fang/*Light Sword* and Diamond Eyes).

Rogue: Backstabbing for up to X4 damage. Dual-wielding with this class is universally agreed upon, as they can't use the big two-handed weapons, and shields are pointless with Stealth and Reflextion. Sword and Dagger are the way to go (Bloodlust/Thieves' Dagger if cursed, Fang/*Light Sword* and Stiletto if uncursed).

Lord: They get a bonus to Dual Weapons skill, but don't do nearly the damage of the Fighter/Rogue.
Valkyrie: They get a bonus to Polearms skill, strongly discouraging dual wielding.
Ranger: They are highly skilled in ranged crits, and get a bonus to the Ranged Combat skill. Not for melee.
Ninja: They auto-penetrate with thrown weapons, making them more suited to ranged combat.
Monk: They are martial-arts experts, and don't need the Dual-Weapons skill.
Samurai: I've never used one, but I hear that they get *Lightning Strike* as a bonus, however, it's not as reliable as Berserking and Backstabbing. They can use offhand swords, however, they won't do the damage of a Fighter or Rogue.
Bard/Gadgeteer: Jack of all trades. They will be mediocre at everything. Don't dual wield. Sword/Shield.

Berserk only matters when you're comparing different classes. If you have X class, and are trying to decide whether to dual wield, it's irrelevant. Also, when dual wielding, Primary > Dual Weapons > Close Combat > Secondary. (This is assuming Primary and Secondary aren't the same skill, and that the character isn't dual wielding thrown weapons.)

Fro what I've read, x4 backstabs only appear at higher levels and are rare. Hence, you can generally only expect to see x2 and the occasional x3. (This improves at higher levels, but caps out at 20.) Also, Rogues don't get Diamond Eyes. (Worth noting that I tend not to use rogue/monk/ninja because I don't like how Stealth works, and in particular that you can't turn it off.)

If you have a Lord, dual wielding is definitely the way to go.

With Ninja, there's a couple factors here:
* Thrown ammo isn't that plentiful, so you're not going to be using it except in harder fights. (Fortunately, a sling will allow the Ninja's skill to still increase.)
* You can dual wield thrown weapons, so the Dual Weapons skill can definitely be useful here.

I wouldn't use the term "mediocre" to describe the melee abilities of a Bard/Gadgeteer. They're actually pretty good at melee, and don't have that many skills to raise (unlike conventional spellcasters). Plus, there's that 20 Strength accessory you can buy from Bela.

It's no wonder that one who avoids rogues doesn't understand them. And yes, four times damage is only a five percent chance, and only at or after level twenty. Backstabbing also increases accuracy, both directly and indirectly, reducing one of the penalties of dual-wielding. A dual stiletto rogue makes a lot more sense than a dual stiletto lord. And let's not even talk about the cheese of stacking backstab and berserk. (Thankfully that comes with not insignificant opportunity costs.) A rogue can do more with an off-hand dagger than anyone but a fighter can do with diamond eyes. See, backstabbing has an expected value greater than two hundred percent, and the best daggers have more than half the damage of diamond eyes. The only thing that makes diamond eyes "better" is that hefty paralyze bonus, which is less good the higher the difficulty. And then, the only real alternative for a rogue is a shield, which probably means thieves buckler or lithe shield. But, at that point, might as well run a spell-casting thief instead. (Philosopher's shield or *light* *shield* would be good too, if you get one.) Shame that backstabbing only works with swords and daggers. Imagine a faerie rogue backstabbing with a rod of sprites.

I'd say dual-wielding is worth it on anyone that can learn the skill in smaller parties. For a full party, one would typically prefer enough damage to bother, and that means either a passive damage boost or diamond eyes. So that means the Western warriors and the rogue. Now the divinity warriors are mostly interchangeable, but if you are going to use a primary skill, might as well use the appropriate class. Thus, if going for dual-wielding, lord is, almost always, preferable to valkyrie. With monk, in a large party, martial arts is better than dual-wielding, for it takes a very long time for mauler/nunchaka to be stronger. Of course, using a nunchaka in the off-hand until punching is stronger and the monk's strength gets up-to-snuff isn't a bad idea. See, using an off-hand weapon with martial arts doesn't build the dual weapons skill, but only get the penalties of like a one-hundred skill. The ninja is a curious case, because dual-weielding throwing weapons isn't terrible. And there is often enough throwing weapons to power a single dual-throwing character, unless one is playing rampage, of course. Some will dual-throw on a lord to build the skill, but the lack of shurikens and poison darts hurts availability. Mauler/nunchaka overtakes martial arts far faster on a ninja. Finally, COC is good, but COC/rod of sprites is even better. On the other hand, I've seen many claim that a ninja is a bad choice in a full party. I disagree, but I'm biased. Ninja is my favorite class. I would, however, like to mention that there is a diminishing returns problem with melee damage. Which is one, of many, reasons I don't like dual-wielding fighters. And a dual-wielding lord has a massive damage problem for most of the game—but he has divinity spells, so who cares? (Well, unless you're one of those people who rush to Bela right after Arnika. And then rush to the castle afterwards.)

The thing about the bonus to dual wield. Over one hundred points never removes the penalty to attacks/swings, but it has a cap anyway. However, over one hundred points turns the reduction of accuracy into an increase. Which is why a lord is a better choice for dual weapons than a ranger, unless you really need scouting or higher ranged criticals, I guess. Only really a concern on expert, though. My current party is still missing a lot at level ten, but it's going to be smooth sailing until the peak from here.

If only the enchanted wakizashi had more kill, or something.

My understanding is that the two multipliers only stack additively, so even if you get a 4x backstab, you "only" do 5x damage (or 6x if the enemy is unconscious or similar), not 8x. It's a shame that the Wizardry series hasn't been particularly kind to the class. The original Wizardry 1 manual hypes up the class as being the most powerful fighter-type, being able to fight extremely well even without equipment, but it falls flat in that game:
* Unarmed attack is barely stronger than a Longsword, and doesn't scale.
* For unarmored AC to be better than armor, the Ninja's level must be unreasonably high, higher than one can reach in the new remake with its XP cap.

In Wizardry 8, the problems I have with the ninja are that:
* Ninja levels more slowly than other classes, except for Bishop, with which it is tied.
* Power-wise, Ninja is comparable to other hybrids; there's nothing to make the class really stand out. (I don't consider Locks & Traps to be a significant factor, as you really don't need the skill, and the other classes that get it have the fastest leveling rate and tend to be valued more for backstabbing or stamina casting.) Not if dual wielding makes the character lose a mainhand attack or swing.

More damage is still more damage, not to mention just how busted bloodlust is inherently.

Throwing auto-penetrate is so good that if throwing weapons weren't hot garbage, the ninja would be busted. C.f. mods. Similar issues arise with dual weapons even.

One can argue reducing the amount of attacks with COC is a viable strategy at times, even if that falls away over time. If you don't see it, you might have never run a cursed faerie ninja through the peak without a plan. I haven't, but one could define wisdom as the ability to learn from other's mistakes. But ignore me, for I am an ignorant fool.

The ninja is the weakest locks and traps class in many ways, but that expands the dimensions of the game, not diminishes. And, at least they come with their own knock knock. Well, divine trap is more important.

Berserk will be combined with Close Combat (an inherent Fighter bonus), Dual Weapons, Sword, Mace and Flail, Powerstike, and Reflextion skills. Thus, when leaving the Monastery, the Fighter will be a beast.
The Fighter and Rogue work as a dynamic duo together at the front of the party. As the Rogue's Stealth increases (as mine has, into the 90s), the heat will be more often on the Fighter, who can be protected with Guardian Angel and Body of Stone (he has the highest hit points, and best armor selection as well).
The Ninja takes as long to level up as a Bishop, while only having one spellbook (Alchemy), vs the Bishop's 4 spellbooks.
Also, the Rogue gets a bonus to Locks and Traps (which doesn't matter, if you don't mind reloading).
I ran a MDP last game with a Bard and Gadgeteer as the "Fighters". They were great until Ascension Peak, where their random stamina-casting levels really fell off (To be fair, most magic fell off). All characters were forced to use physical ranged damage against similar level enemies.

I think that magic is still good around level 25, when you can use high level spells at high power levels, and enemy levels don't yet outpace it. It's only if you level up further that it becomes a significant issue, as you have no higher {spell, power} levels you can use to keep up with the enemy's increasing levels. (And I consider party member levels past 25 or so to be beyond the scope of where the game was balanced.)

Fighter and Rogue have no magic, and in particular that means no portoals. I like having lots of portals, so it can be hard to fit those classes in the party. (Then again, Bards and Gadgeteers also lack portals.)

Also, does the Fighter *really* need the extra protection, given their high HP and good armor selection? (I've actually gotten to the point where I no longer use most heavy armor, preferring to sacrifice AC in favor of a lighter load.)

You are "supposed" to be able to cast level 7 spells at power level 7 at level 24, which isn't even possible with specialist casters, save for a few select spells. This gives power to the Bishop, who can't either, but at least he/she can learn all level 1-5 spells guaranteed, and if you're smart, you will pick the best level 6 and 7 spells.
I have long given up on "perfect" Bishops, because who wants to carry a Bishop to Arnika, and really, all over the world, to visit every vendor, and then have to slowly train every realm and spellbook, and then Powercast?
What's way more fun is to have your Bishops slowly train their realms (2 spellbooks at a time), until they're competent. They can then buy almost all level 1-5 spellbooks, and slowly train their two ignored spellbooks. They can then say that they have the most powerful spells in the game, while having maxed 4 spellbook skills, and 6 realm skills (probably beyond what the average W8 player wants to do). However, it's more fun this way.
Party levels beyond this point increase the enemy spawn levels at Ascension Peak, but also allow you to better handle 95% of the game. As far as I know, a few wilderness areas (particularly, the Southeast Wilderness, Mountain Wilderness, and Rapax areas), can spawn higher level enemies than 25. The Mountain Wilderness can spawn level 30ish sprites, and level 34 Molten Scorchers (not a rarity, a very common enemy).
I was going to say that. The Fighter and Rogue have the distinction of being the only two classes without magic (not counting consumables and item charges, which anybody can use). Thus, they were programmed to be excellent at their one thing, melee combat (and not too shabby at ranged combat, either).
I had the encumbrance debate with myself, and decided to max Strength for all six party members, so that it isn't an issue later. Everybody will have Powerstrike, and be able to melee bosses.
The Fighter, although very tough, still can fall prey to Paralyze/KO/etc. Therefore, casting Bless is always good, as well as Guardian Angel, and Body of Stone when I get it.

Actually, a level 18 full caster can cast level 7 spells at PL 7; it's just that the change of failure is pretty high, at 42% plus whatever comes from skill.

At level 24, that 42% goes away entirely, leaving only the skill based chance. While (typically) non-zero, it's low enough to be reasonable much of the time (though in some cases, most notably with Restoration, I wouldn't bet on it), and it's lower for specialist casters.

It can still be an issue later, depending on what you're carrying. All that heavy armor, ammunition, and those stamina casting items really add up when it comes to weight. Then there's items like the Giant Silver Nugget (which could easily catch players by surprise) and the Sledgehammer (which you can't even drop without putting into a container; this can be a problem if the player can't figure out where it's supposed to be used).

For the party I was playing, Power Strike doesn't fit everyone (only one of my Bishops is getting it), as the skill I've chosen to get for everyone (including the Valkyrie) is Power Cast. On the other hand, I haven't played for a while, being distracted by various incremental games, as well as Spiderweb Software games (Geneforge 1 - Mutagen and Queen's Wish 1).

Thankfully, items like the Giant Silver Nugget are entirely unnecessary, as are all custom items (The Fighter, Lord, and Valkyrie can get the best armor in the game, and those 3, plus the Ranger and Samurai, can wear the Infinity Helm). I just hate litter, and force myself to pick up all "white dot" items lying on the ground, to eliminate visual clutter.
If you're not a total noob, you will know instinctively what to do with the Rusted Sledgehammer (I know I did). I believe that it's unnecessary to both get into and out of Marten's Tomb.
My Valkyrie and Ranger are ignoring Intelligence on the premise that:
1. Intelligence by itself is almost useless (helps a bunch of skills go up faster, and gives a small Mental realm resistance above 80)
2. Powercast is much more suited to offensive magic; The Valkyrie and Ranger have the two most defensive spellbooks (Divinity and Alchemy respectively).
3. The Valkyrie and Ranger can serve as temporary buffers, filling in as the combat-only buffs, such as Element/Soul Shield, Bless, Rest All, Heal All, Body of Stone, while the Bishops severely punish the enemy with their magic.
Finally, getting a second Staff of Doom will probably not be as hard as you think for the second Bishop. There are set Rapax Corpses near Rafe's Cell in the Rapax Rift that have a 10% drop rate. It might take about an hour or two (just have some booze near your computer, you'll eventually get a second SOD).

I'm not so sure about that, particularly if it's your first time ever in the Sea Caves and you aren't looking things up on the internet.

Or, the player could have trouble navigating and therefore miss the spot where it gets used.

(Before you mention the way out, keep in mind that many players will just portal out as soon as they get the Destinae Dominus.)

Remember, there are first-time players, and they don't have the years of knowledge that us veterans do, and the game should still be fun for them.
I'd rather spend that time doing something fun or making progress instead of just playing the lottery over and over.

The "lottery" looks like this:
Jan-Ette: Small chance for a *Light Shield*, keep talking to her.
Buccaneer Ghosts X7: You can farm *Light Swords* and *Light Shields* from them, with a 20% drop rate.
Rapax Corpses X2: 10% drop rate, twice as hard to farm a Staff of Doom.

Smashing down the wall with the Rusted Sledgehammer reveals a locked door, so you still can't get in using this method alone.
Once you're met Marten, using the key he gives you on the locked door is a formality, as you can get out many ways, not just by portaling out.

That's not the actual chance of getting the item you need. Rather, that's the chance of having a chance to get the item you need.

Also, if you don't get the drop, you have made no progress toward getting it. (This is unlike, say, XP, where you've made some progress even if you don't level up, or skill increases, where you do get some progress (and, unlike many of this game's item drops, can actually try again without a reload).)