I think that pretty much covered it. There really 
is no purpose that I know of. However, if it was 
a hanken cel, that means it was the original art 
for a "print" used on CD/LD/DVD covers/cards, 
etc., right? (I'm not sure about that.)
 I would be VERY wary of something that said 
there were only ten of something made. I had a 
reputable Japanese dealer tell me that certain 
UFO catchers were made in qty's of 5-10, when 
I've actually seen more of them with my own eyes 
in the states than he mentioned. ^.^ If you're 
referring to one you bought from Taro, I'm sure 
they're legit, but I'd definitely still require 
some sort of guarantee/certification- esp. 
considering how expensive those repro's or 
hankens were.