Before you mention, Yes, I know there is already a lightsaber weapon available at this thread.
http://www.blockland.us/smf/index.php?topic=15411.0My suggestion is this.
Instead of making the blade as part of the model (as is the one mentioned above), why not just model the handle and have the 'light' bit be made of a single emitter? Similiar to the emitter of the laser it could come in different colors (red, blue, green) and I suppose you could model different handles.
Another bonus of my idea is that perhaps you could add in an on/off feature so the emitter could be disabled with a key press further adding to the realism.
Thats my idea. Any comments? Additions? Reasons why this wouldn't work?