Gaffer Tape said:

Well, yes, it's certainly not a character study, but if you establish the precedent that a character can make a choice between good and evil, and that they are not simply stuck on one side of the line or the other, it implies that the characters themselves are not inherently one or the other. You say Vader is non-relativistically evil, but Luke constantly says, "There is good in him." And it turns out he is right, which means that Vader has both good and evil traits. True, there is not really any good example to show this. We don't see any struggle until the very end, so I'm not arguing that it did a good or deep job from a relativist angle, but the concepts certainly existed.

Perhaps we're not in sync as to the use of the term 'moral relativity.'

I'm referrinig to the philisophical conceit that good/evil are not universal truths, that situation, culture, and tradition are part of what is categorized as 'good' or 'bad'. I'm referring to the idea that morallity is subjective.

No matter Vader's personal journey from good to bad to good again, the lines of good and bad are still very sharply defined and objective. "Star Wars" never asks us to see the destruction of Alderaan as a 'good' thing from Vader's point of view, nor is torture and casual murder that Vader does somehow justified from his religious views ("The Sith Antidiscrimination League"). These are all universally seen as 'bad.' Vader himself would probably see them as 'bad' and just not care, given that he's down with the Dark Side.

The closest the OT comes to moral relativism is Obi's line about "from a certain point of view" and even that is (I think) just meant to be his justification for his own lying. In the PT Palpy tosses out some vaguely moral-relativistic concepts, but again I think that's meant to be seen as just him lying to Anakin, as Palpy's ultimate goal is simply revenge and 'unlimited power.'