I was listening to the Original 1977 soundtrack yesterday and the track “Ben’s Death and Tie Fighter Attack” came on and I was picturing the scenes and thinking about that duel and something occurred to me about the Kenobi finale duel. Using the force can be exhausting. What we see both those men do in that duel would require great effort. A casual viewer might assume that Kenobi is still in a position to fight, but consider this, his withdrawl after leaving Vader injured and kneeling is because it has been fought to a draw. Neither has energy to continue the fight. Obi-wan is not positive he could take Vader at that moment because he is drained and trying not to show it. He leaves in victory, but only because he momentarily bested Vader and give a chance to recover there is a real chance Vader would win if the duel continued. And it is not the Jedi way to strike down an opponent when they have been bested. Dealing a death blow in combat is different, but cutting your opponent down when they are kneeling and reeling from your attack is not the way things are done. Civilized and honorable are the hallmarks of a Jedi. They fight by a code that has rules and it is uncivilized to break those rules. So Kenobi walks away from the duel in the Kenobi finale because he is at the end of his energy and needs to rest and he has fought Vader to a draw and left him reeling from that final attack and unable to, at that moment, continue. So rather than debating why Kenobi let Vader live, I think that it was both Kenobi following the Jedi code of combat in a duel and that he used so much power in that attack that he knows he cannot keep going. And while Vader still possesses his lightsaber, this is at the same point where Luke turns from facing Vader and confronts the Emperor.
The other thing is that I love Alec’s portray in ANH. There are so many subtleties that play into the saga as it expanded. He expression when he tells Luke about his father and his expression when he looks over at the three younger people as they are ready to board the falcon. None of it was known at the time, but now that the saga is complete (following Ep III) it looks like he is uncomfortable with the tale he is about to tell Luke and then pleased that the twins are back together. And Vader didn’t believer him when he boasted of becoming powerful. That look of peace on his face as he raises his saber to leave himself vulnerable to Vader’s blade. Alec was a master and gave a future proof performance. Too bad he didn’t win the Oscar he was nominated for.