Quote Originally Posted by feioncastor
So what about a moogle? I know they weren't in that many FF games, but I think they are unique enough so that they don't resemble anything else. I don't really know of anything else.
You know, they were in FF5-10 in some form or another. Everything from playable characters to playing cards. I see no problem in going with a moogle. It's something that says FF without pointing to a specific game.

Other than that though, I like the suggestion for FF9's crystal, or you could go with the specific logo from you favorite FF if the artist can do it. Geting Final Fantasy in Japanese lettering might be good too, but you want to check and double check the design before anything permanent happens.