Blue lightsabers are a reasonable idea. Also, in keeping with the idea that the Jedi were protectors from a more idealized time, I imagine they would have been more like Samurai than soldiers. For example, many would be in service to the reigning monarchs of the frontier worlds like the King of Alderaan, and these were the only ones known as Knights as opposed to people like Yoda who were always unaffiliated teachers and mentors. These Jedi Knights would wear black like Luke in ROTJ.
If the Empire are like Nazis that rose to power, then the Jedi should be like Rabbis who walk around with katanas.
Not sure about them wearing black though.