After skipping him on my first two playthroughs (years ago), I finally nabbed Vhailor and I'm testing out his much-vaunted combat prowess and I am... confused. And underwhelmed.

He's horrible, horrible as a tank. Which is weird, because you would think the one thing a living suit of armor would be good at is sucking up damage. Looking at his stats, it isn't hard to see why. His hitpoints aren't better than the other fighters, he can't cast blur like Dak'kon, his resistance to piercing and missile weapons is good but not nearly as good as Morte's resistances, his base AC is only 2 and the only way to bring it down is through rings--no tattoos and he can't seem to use any useful bracer. And for some reason Submerge the Will (Zerth version of Shield) doesn't bring down his AC at all! So he's stuck with an AC between 0 and -3 depending on the rings you give him... horrible, just horrible. He dies *so* quickly. Annah, Dak'kon, Morte, Nordom and TNO are all better tanks. I'm not sure, but even Fall from Grace might make a better tank given 2x stinger earrings, the regenerating bodice and her ability to auto-cast heal spells on herself.

And his damage? Not bad, but pretty underwhelming. By the time I get him, I've got Dak'kon with a STR of 23 (Unbroken Circle upgrades, plus greater strength tattoo, plus 2 lesser strength tattoos, plus dread bond... and he still has an AC of -10 with a Submerge the Will!) . That gives him +5 to hit +11 damage, and he can hit a whispering flask to get 25 str for +7 to hit, +14 damage. Vhailor is stuck at 18/51 str and he can't use tattoos, or the dread bond, or whispering flasks, and Power of One never seems to have any effect even thought the description implies I should be able to bump it his STR up to 21 or so. He attacks a little bit faster than Dak'kon, but it's nothing special and unlike Annah or TNO or Morte he can't use special weapons that have interesting effects like stunning, poison, confusion, etc.

I seriously think he may be the worst character in the game for combat. Meh damage, no special powers or interesting-effect weapons, and more fragile than everyone but Ignus (who is fine remaining in the rear anyway.) And yet every single walkthrough and comment I've ever seen about him seems to imply he's supposed to be some kind of god in melee.

Am I missing something important here?

(Note: I usually play with the combat difficulty slider at the max and I have the tweak pack installed with most of the defaults selected.)

I haven't used him much but even if you don't want to keep him around, he can still give you a permanent +3 str boost (boosting you from 16 to 19 str for example)

(the size of the boost depends on how lawful your NO is)

Well, it can't. Shield and Submerge the Will set base AC to 3 and 2, respectively, and since Vhailor's is already 2, they don't have any effect on him. IIRC, whispering flasks are restricted to usage by githzerai, not on githzerai. Dak'kon should be able to buff Vhailor with it just fine. Wasn't it restricted to 18/00 in the fixpack? Anyway, there's Improved Strength for greater buffs.

Vhailor's problems can be blamed on him only being level 9 when you recruit him, which, depending on how you've been playing, is a bit too low for a single-class character at that point of the game (and you don't have much opportunities to grind... maybe those abishai in Baator...). But yes, unlike other fighters, he is a more "generic" one, so if you're used to your tanks having combat enhancing abilities, whether it's magic assistance, naturally high resistances, or weapons with special effects, he does seem weak in comparison.

I would note, though, that he starts with 18 Constitution, so equipping him with the Aegis of Torment gives him regeneration, in addition to more HP, which should've improved his survivability a little.