Here's my take:

Berserk attack
Probably one of the most powerful skills, though it's quite bad early on

Stamina Regeneration
Tough to judge, since all those regeneration skills don't do much in combat; probably really good though

May KO opponents
Does anybody know what KO% this adds? Anyway, on the fighter it's a bit wasted, since he is more of a killing machine

HP Regeneration
This CAN be good, since it compensates ANY -HP item you equip, but it's also somewhat wasted on the Lord, since he doesn't have a lot -HP items to equip

Cheat death
Okay, but somewhat overrated. At some point you get resurrection powders in abundance, so this is not really that useful. Quite good early on though.

Scouting
Useful I guess, but not really crucial (you can always search)

Ranged Criticals
Great stuff; this one makes "Ranged Combat" the ultimate skill for the Ranger combining the actual Ranged Combat and Ranged Critical Strike

Lightning Strike
Hard to judge, but I guess it's pretty mediocre, given how luck depended (and rare) it is.

Fearless
Fear is one of the less dangerous conditions, but immunities are always great.

Thrown Criticals
This is probably the only thing that makes Throwing weapons worth it for the Ninja, considering how little damage they inflict

Thronw Auto-Penetrate
Supports Thrown Criticals, probably really good

Effective while blind
Blindness is annoying, so this can be great especially against those Caustic Vines; I don't know HOW effective you are though... Does it mean you get some of the penalties (double damage when hit), but not all of them (like To Hit)?

Natural damage resistance
Very good, though maybe somewhat wasted on a class with Stealth.

Backstabbing
Killer! Maybe overpowered, especially with good swords.

Gadget making
Great of course, though to me this doesn't feel like a "Special Ability" (more like a basic ability for this very class)

Increased recovery while camping
It's twice as fast I think, which is quite useful, especially for magic users in your party

Pray for Miracle
It can be very useful, but its randomness makes it quite underwhelming. It's interesting, but often it's a round wasted on something that may not even work at all.

Potion making while camping
Mostly those potions are quite mundane, so I feel this is quite useless.

Remove Curse
Almost useless, since he can get the spell quite easily, and the ability is not really needed often

Dispel undead
Okay, but rather underwhelming compared to stuff like Banish... and even without Banish you're mostly better off using some other more effective spell

Mental condition immunity
For some strong fighting class this would be amazing; on the Psionic it's mainly useful to keep him sane in order to heal others... so yeah, probably not bad

5% bonus to all resistances
It sounds great, but at some point the Magic users will be quite resistant anyway due to their realm skills, so it's not that much of a deal I think

On the other hand, this saves having to spend a turn to revive the character. Late game, when you have Restoration, it becomes easy to restore the Valkyrie to fighting condition (restore HP, restore Stamina, *and* cure unconscious). At higher levels, I have seen it make things like Death Bombs. (Of course, I never actually used said death bombs, but that's another story.) Also, don't forget that you can sell the potions for money; this ability is better for making money than Pray for a Miracle at any rate.

Note that it seems that a fair amount of real time needs to pass before you can make another potion, but once you can, you will make it as soon as you start camping.

It can, however, make inventory management more annoying, especially when it makes an extra copy of a potion you are using with Alchemy to make money. Dispel Undead is nice because it can paralyze in addition to doing damage, a combination that no other spell gets (and undead are not immune). Also, it affects all undead creatures in range (though be aware that it is only Thrown range). According to patch notes, this ability will prevent the character from wasting turns "stumbling blindly", provided that you are playing 1.2.4 (the version you get from gog.com) and not the original release.

The "can cast Alchemist spells while silenced" is worth something imo but perhaps you don't like that one?

That's actually not a class ability, but rather an effect of the Alchemist skill. Even Bishops can cast Alchemist spells while silenced.

Yeah, I don't really consider this "silence immunity" a special class ability.


Btw, how would you judge the abilities of the various races? The thing is, in the Cosmic Forge editor you can also assign those to classes, but obviously some seem overpowered, not very meaningful, or simply bad.

Positive characteristics:
==================
- Faster spell points regeneration
- Android immunities (vs. Irritation, Nausea, Fear, Sleep, Poison, Disease)
- Armor class bonus (+2)
- Acid Breath
- Dwarven damage resistance (how does this compare to the Monk's damage resistance?)

Negative characteristics:
===================
- Slower spell points regeneration
- Reduced Carrying Capacity
- Equipment weight limit
- Cannot change classs
- No magic

For modding purposes I think only two are really interesting (faster and slower magic regeneration); AC bonus looks overpowered in most cases, except you combine it with some other negative characteristics. Android immunities are insane of course, and most of the others are not really that interesting.