Sadly, I fear you may be working to US rules here, CC. Me, I'm working to the universal Tank rules of custody: stuff the kid's interests...hand him over.
It is true that possession is nine tenths of the law, of course. However, a dirty great big sword in the hands of a Ninja trumps possession every time....
LabRat (who notes, ominously, that her house is now Ninja free...wonder where they can have gone...?
)
