Himura_san - damn it, knew someone would do that...

Einzelgänger - True, but a huge shuriken with 4 blades thats in your backpack doesn't dissapear the next day.

lasaire - Good point, but the Manga covers shows alot of stuff, and even a few pictures where they look older (itachi age older)

But Kabuto uses that Kunai more then once. At least we see him fighting with it.