The part about the decapitation confuses me. I assume only axes and swords get that part, but do Warhammers also get the +25% damage from a power attack?

Warhammers can also decapitate enemies.
All 2H weapons benefit from the perk.

...Warhammers can decapitate enemies? no... That seems silly. Warhammers can do a lot of things to heads, but they're closer to "explode" or "Pop" than "decapitate."
Of course, you're right that they can, I just checked when i read your reply. But it's still silly. anyway thanks

The hammer could just knock the whole head off. I guess thats why they consier it able to decapitate