I wouldn't worry about it. I'm not even using the lightsaber I started with anymore and I am only level 12. I ran the Black Talon flashpoint once and got a nice custom (orange) lightsaber in there.
I am sure there are many more to be had.
Stupid question, and one that I am sure I could figure out by trial and error, but...
Does anyone know if there is a limit on how far apart, in levels, party members can be before one or both have XP gains affected?