I don't think the Imms added these to be all used by every AP. It's more of a bunch of different cleaves for different weapons, so Axe isn't the only desirable unholy weapon. While I'm sure you could 7 different weapons in a fight, I don't think that's what they were thinking when they put this in. Also giving spear and polearm and flail and whip both two abilities each is going to make them much more favored then the other weapons.

That which does not kill us,
makes us stronger.