Well maybe it can retract and extend with the R animation (taking weapons in/out) button.
And jedi suits can easily be made since you've only got 2 pieces of equipment to even put them on (body and head).
Clone/Storm-troopers and blasters are a must if you want to see Enclave/Brotherhood like battles (imagine lots of them running, shooting, and taking cover).
EDIT: Now that i think about it, Fallout 3 is certainly lacking in specific resists, I think it may be rushed a bit... (It lacks specific resistance to certain attacks, like power armors would show in description the resistance to normal bullets).
And make the lightsaber 100% chance to decapitate anyone with it, It IS a lightsaber afterall.