[Taqwus]

A Bane Lord equipped like that is indeed vulnerable to fire (incinerate comes to mind) and lightning, as well as maggots and other anti-undead fun.
A horde of mannikin / mandragora could perhaps also be nasty; a wraith sword shouldn't be able to restore fatigue off of them, and each Sleep Vine gets 3 attacks per turn causing 33 fatigue on a hit.