I've just bought two teal-colored katanas that came with only one set - 8509 (Robo Riders):
http://www.brickset.com/detail/?Set=8509-1
They sure are unique, because they were in only one set (released 10 years ago), but I don't know anything about their value. Is this piece anything interesting? Also, I'm not sure how to use them. The strange colour (teal) makes me wonder if they match any historic themes, such as ninja. I'm currently using the swords as some kind of a 'sacred treasure'. Two sacred teal katanas, yeah!
Any information about the value or possible use of those strange katanas?