Quote Originally Posted by Kraco
I don't know why Kenpachi's sword looks so worn. Sometimes I have thought it's because he doesn't know its name - but not so that it couldn't heal itself but rather as a sign of a protest. Zaraki has abused it for ages without bothering to know anything about it. However, it can heal itself just fine, because it was cut nicely in half in the final clash of Ichigo and Kenpachi. If it couldn't heal itself at all, Zaraki would have been fighting with a dagger for the rest of his days. But such wasn't his fate and later against Tousen it was just fine.
On top of that, don't their zanpakatou return to their sealed form when they're broken in shikai and bankai? I can't remember the last time Ichigo had his sword broken, but if it has been since he got his shikai and it didn't seal back up then my point is invalid.