[DrPraetorious]

- If they don't have Torso slots and you put Torso armor on them, then they can't take it off. You can certainly leave it at Enc-0. Should chaos armor be immune to Rust Mist and Armor of Achilles? Maybe it should.
The chief concern is that natural prot values cannot be boosted by an earth blessing.

- Pump their MR and possibly hit points (for nurgle).

- You could add a "horseman's flail" or a "light flail", if you wished. The 1-H flail is for use by giants and Gods (like the Mother of Rivers.)

If you're going to give them an Admin-20 capital, that's potentially workable, but a 10% reduction in the costs of capital only units might be apropriate, to compensate for the lost gold revenue. You also might wish to give them superior fortress options elsewhere - the Motte-and-bailey and the Citadel are both excellent forts that you could claim would be built more or less anywhere. The Wizards' Tower is a secret super-cool fort type that you might allow them to build, but that'd be weird.

What you really need to do is run some combat tests with your mages and thugs, and see how they do.