One would think that the Blighted Plague soldiers (At least most of them, not super high-tier) would simply be raised from fallen enemies. Fallen enemies, as I take it, usually fell in battle. Fighting. Wearing down their weapons and armor. Then dying. Rather blunt view on that, but I'd think that the Dread Lords, mean as they are, wouldn't exactly feel like... Buying new stuff for their men to wear. They'd probably just say 'Use what you died with', even though it might be of suckish quality. That's my explanation of it, at least.