for having a sword.  Funny that Jubei (who is not a samurai, but a
ninja) uses a katana and not a ninja-to

Are you sure Juubei's a ninja?  He doesn't seem to act much like one.
I always figured he was a ronin.  

My brother, who first informed me that Jubei (as well as the other two main
characters of Ninja Scroll, the poisonous kunoichi and the aged sensei) is a
historical/mythical figure, described Jubei as a younger son of a Daimyo
(and so entitled to wear the two swords, though he only seems to wear one)
who runs around disguised as a ronin, for no particular reason other than it
being a handy way to encounter adventure.