I've always found it funny how great the sabers looked in ESB and how bad they looked in ROTJ. (and I'm talking about any versions of the film, no matter what color they are) They usually tend to get things like that looking better as time goes on, not worse... In ROTJ, Luke's is too fat and bright, and Vader's is this skinny pink stick with barely any light in it compared to Luke's. Compare that with the end of their battle in ESB, where I think the sabers look great, brightness and size-wise.