What's the deal with piercing damage?

All I can tell is that it's a physical attack that has more resists vs it (Bonelace armor)

So why would you ever would use a piercing axe over a regular axe, is there some kind of innate bonus that I am missing?

i could be wrong as i have no axe weilders but i was under impression that all axe damage was piercing sword is slashing and hammer crush ...if im wrong i aplogize but hope that helps

Axe is slashing like swords with the exeption of the piercing axe.
Thats what I heard anyway.

Axe is slash unless it's listed as pierce. Chain/Leather can be pierced easier than slashed (at least in every other MMO I have played).

I did a few experiments with my Pierce axe vs Slash axe and can't really find the answer yet.