You know, honestly, even a katana that doesn't hold a live blade can still be a dangerous weapon. I mean, the thing still has a very sharp pointed tip at the end that would easily slide into someone's belly with the proper application of force *evil thoughs mirrored by the evil grin* Ummm... anyway... for the most part, I think the rules as they stand are suitable and fair. I remember a certain someone having a six foot Masamune that followed all guidelines and there was no problem.
Anime_fan, if you really need a katana for your cosplay, I have one that would follow the rules I could lend you with collateral. Not sure it would fit, cause I'm unsure who your character is, but if you'd like I'll send you pics