I realize they have to have this epic battle in Ep. III, which I greatly look forward to. I've always thought they'd fight right before the end of the movie. Anakin would fall, "die", and be saved by Palpatine. He would then take the new name Darth Vader with the new costume. Obi-Wan would think he died. After all, he hides the babies from the Emperor, not Vader.
OK, so good so far (barring minor/major changes to that )
So when they fight again in Ep. IV, Vader says "When we last met, I was but the learner; now I am the master." To which Ben replies, "Only a master of evil, Darth."
Okay -- so Ben has to know that Anakin is Darth Vader. (Also evidenced by his "point of view" on how Anakin became Vader, which he tells to Luke). I doubt he gleamed that knowledge in his 20 years of hiding. Thus, he also has to know that he's been up to evil things. Does this mean that Anakin was Darth Vader when they fight in Ep. III?
Which brings me to my next question: if they fight when Anakin is Vader, then he is in fact NOT a "learner" anymore, right?
So, has my theory about them fighting at the end of Ep. III, and us not seeing the fully-clothed Darth Vader until Ep. IV withered and died?
Thanks for your insight.