User blog comment:Ichigostop/Marco's ability is unique?! yeah right../@comment-3273232-20110428230746/@comment-2106167-20110429123205

Users of Logia-type Devil Fruits DON'T regenerate: what they do in order to defend against incoming attacks is to turn their body in their fruit's element in order to completely AVOID being struck. Take Ace for example: after he was struck by Akainu's magma fist, he DIDN'T regenerate, because the damage was done, and even turning into his fire-form wouldn't have saved him.

As for Haki attacks... Well, that's not completely clear, but according to many people, Akainu used his Haki against Marco's and Vista's to NEGATE their Haki-enhanced attacks and AVOID the blows as usual... Though he might have felt them a bit, given that he was quite annoyed afterwards...