As far as I remember his hand just stopped at haku with the bright flash of lightning on top, no piercing goodness... And then there's a bunch of "little" details like the sound nins arm which got blown off etc.
http://img55.onemanga.com/mangas/000...0101462/20.jpg
-edit-
After youtubing hakus death there is quite a lot of blood, but kakashis hand doesn't really enter his body.
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