This is the crux of this whole discussion and the thing that drives me bonkers. Why should the definition of mundane flex? What is the intrinsic value of a fighter that doesn't explain how it does things? "Mundane" is a hard place in enough people's minds, and I don't see what's lost by abandoning it.
It's so much cleaner and easier to design technique systems with phlebotinum, so we could just do that and not have to keep having this argument.
If for no other reason than I don't want to have to explain that no amount of +2 to damage or saving throw bonuses matter in the face of stoneshape or fly. I think people should be fighting at high levels, with weapons and everything, and that they should grow wings and balance on air and cut through space and time, because that's the sort of stuff that happens there.