Board Thread:General Discussion/@comment-10587310-20140409095234/@comment-8986886-20140409114852

If Kenpachi had forgotten the name, and abilities, of his Zanpakuto, then he would've forgotten about his first fight with Unohana too. When fighting in the Muken, Unohana remembered that encounter, and that Kenpachi was holding back at the time. Neither of them would forget the scars they received that day. If the skeletons are a hint to the Zanpakuto's abilities, I can't really say; it's been a while since I read that chapter.

Also, whether "Nozarashi" is Kenpachi's Zanpakuto, or just an ability, then it seems to have been decided on the first option. It's already been added to his page: