Adamantim can cut through anything.  It cuts like a hot knife through butter when put up next to steel and etc.  But What makes that skin behind the steel capable of dealing with the pressure that comes with the cutting of that mateoutrial.  Even at some point when cutting through something as light an fluffy as a loaf of bread some kind of outward force needs to be place upon the cutting surface.  So?  In kind does Logans healing factor give him some kind of super callosed skin between the knuckles that prevent this kind of outside force.....or is his healing factor so quick that once cutting through he breaks tendon and bone and heals quick enough to not notice the pull of him pulling through a dense piece of material?   Just Saying??