Truth to be told, these aren't considered 'offensive' - NB is 'disabling', while the other is a summoning spell. Harm is offensive though (but it is funny to be used by druids).
Don't think that it's a bad idea at all, but it would open up further possibilities: simply think on demons/devils, devas/fallen devas for example. These would need specific dialogues as well, and that would be truly beyond our scope.
For now at least.