damn, I restarted 3 times just for this post lol.

Axe and flail have random number in their fomula, sorta like a dice to determine the damage. According to the BM:

Flail and Axe damage = F * Weapon power; where F is a number ranging from 1 to your Physical Attack.

And yes, that's the only answer.

btw, I think there's something about throwing them at enemies, something about 'confirmed highest damage' thing. Someone clear my mind about this.