flails or war hammers?

[True_Moose]

It's time for the form-letter response: there is none! But that's not the answer you were looking for, right

A couple of things to consider. First of all, GWW, and Improved Haste mean that Belm and it's ilk (Kundane, Scarlet Ninja-To,) become obsolete. That leaves us with two kind of off-hand uses: offensive and defensive. The best offensive weapon for the off-hand is, without a doubt, Crom Faeyr. It just adds huge amounts of damage to your main hand, and doesn't do a shabby amount on it's own. On the other hand, it gives you no defensive abilities whatsoever.

On the other hand, an off-hand weapon can be almost shield-like in nature. Cue: Defender of Easthaven. Very pretty bonuses to damage resistances, as well as an AC bump for good measure. Hardiness is stackable, so have fun. Problem: only a +2 (IIRC) weapon, and adds nothing to the main-hand at all. Almost like a glorified buckler that does a bit of damage (neglible come ToB)

What is a bit of both? The Equalizer. Alson discovered a long time ago that the Equalizer adds its combat bonuses to the main hand as well. Since many things (particularly with a fixpack like Oversight installed) you'll be fighting have extreme alignments, this is great offensively. Plus you get several nice immunities (particularly to mental spells.) This is probably the off-hand you want to go with.

If you're not going to go with the Flail of Ages, then I think the Axe of the Unyielding is once again, your best bet. Regeneration plus the CON bonus is excellent, and it does a lot of damage. Vorpal effect is pretty too. Use other quick slots on:
2) Runehammer
3) Storm Star
4) Ilbratha

Why these 3? Runehammer has that great instant kill effect you know and love. Use Mace of Disruption prior to that. Sure you won't fight that many undead afterwards, but when you do... Storm Star is great for dealing with low level mobs. Throw down a GWW attack and get 2 or 3 chain lightning spells going and watch as you carve through armies. Ilbratha is a purely defensive tool, for the mirror image.

[Desuma Malevois]

One small point - Defender of Easthaven lists as +2, but it's actually +3 (and IIRC the Baldurdash fixpack fixes the item description so that it lists as +3).