I think light sabers are as canon as anything in the proto-Traveller-verse. In the OTU, and I guess maybe with "thingmaker" in T5, you can cobble one together, but possibly not for strict OTU interpretation.
Again, as per the original premise of and for the game, it was meant to be e generic do-all scifi RPG that could mimic a variety of settings; i.e. season to taste. I think at either that back of 76 Patrons or Citizens of the Imperium there is an example of Luke Skywalker and Darth Vader statted out, complete with 4d6 broadswords and broadsword skills as "lightsabers"
… so there.