What is the most potent warrior build?

One or two shotting everything upto level 3 is standard. Deths are just about the only thing on that level that can't get taken out in two hits, normally. Ignore the tutorials advice on taking Viking if you want to melee with a splash of magic. +2 damage a hit isn't enough to take up a whole skill slot, and there aren't many times Voltaic resistance is useful. Burglary would be better since it offers a good hold, XP via free lockpicks and a great escaping skill for when you need to get some distance. The debuff isn't so expensive, and you will really only need it on tough enemies, so you can take Fleshsmithing with out any mana support and be perfectly fine, so long as you keep a few high quality drinks around for when you actually need them.

 

I personally managed to use a warrior build revolving around the following:
1) Staves
2) Dual Wielding
3) Necronomiconomics (Primarily for Pact of Fleeting Life and Mark of Cthon. Didn't bother with the rest of the tree until near the end of the game)
4) Blood Mage
5) Archaeology
6) Alchemy (Mostly for potions and the Fruitful Staff)
7) Astrology (First skill is a life-saver. Syzygy and the other buff aren't half-bad, either)

The build was surprisingly successful, since I managed to nullify the damage from Pact with the aid of my Astrology buff. The bonuses from Mark and Pact are definitely noticeable (considering that staves give spell power, and the effects of both skills rely on improved spell power), while the debuffs, when used sparingly, worked wonders. They're still not amazing, but it works quite well. Zoos are somewhat troublesome, unless you decide to grab the final Necro skill. Which is well worth it, in my opinion.

Now, this isn't a "pure" warrior build, but the essence of it still exists: whacking things at melee range. Its effectiveness kinda depends on your luck and skill (I managed to find quite a bit of rusty stuff and aluminum powder on my run), but I managed to beat Dredmor on GR+PD, so I don't see why this couldn't work.