Mmmm, it'd certainly be powerful. I can't help but feel though that the reason they didn't do it before, in either game, must be something other than them never considering it though. Seems to obvious.
They might've just considered it too powerful honestly. Consider a knight with zombie. In melee range, hitting him heals him + poison the enemy + let's him hit back + sets up for combos using posion cloud or pool blood makes. Make him fire resistant and then you have a walking poison barrel basically that lets you explode everyone else around him and posion enemeies. Seems like it could be easily abused -> not that that's bad since I imagine to fully exploit it would be end game stuff to make you 100+ fire resistant
