I'll continue to play along in devil's advocate role. To be perfectly clear though, I am not arguing with you at all, Nicklab. Having fun geeking out over Star Wars trivia and analyzing these movies we like enough to be talking about 40 years after the fact. I appreciate the conversation!
The way you've analyzed this is very much from a standpoint of hindsight. But put yourself in that theater seeing the film for the first time. Because the scene plays out quite differently when you look at it from the standpoint of a fresh viewer who doesn't know that Obi-Wan has been studying the Force, and how to maintain his identity.
Except for the fact that it is Ben's disembodied voice that Luke reacts to when giving up his "revenge shooting" of the Stormtroopers (and I assume, attempting to hit Vader.) Once the viewer hears Ben's ghost voice, they know Ben isn't "dead." When he comes back during the Trench Run, it's nowhere near as powerful as when Han Solo does. Because we already know he's there, he even told us he would be just before he disappeared: "If you strike me down I shall become more powerful than you can possibly imagine." So I don't think its hindsight helped along by the shoe-horned explanation from ROTS. To me even at four years old when I first saw it, there was never that thought that Ben had been killed by Vader.
As for the duel? Ben is having a hard time holding his own. Both he and Vader are not in top dueling form, and Ben has largely been on the defensive while Vader has been the aggressor. The only indication we have that the duel is taking a toll on Vader is that his rate of breathing has increased. Then he sees Luke and the others trying to escape. He knows that giving himself up and the distraction that may cause Vader might be the only way to ensure that Luke and Leia can escape.
Agree on all points here. He is losing the duel in that he never has the advantage (no high ground on the Death Star...) He turns the duel into a distraction to get the kids out of the Death Star.
I do think there's the potential to make it a heroic sacrifice, Ben redoubling his efforts to actually finish Vader while knowing full well he may be struck down in the bargain, as opposed to how it plays out now (which is essentially Ben pulling out a large pair of spectacles and saying "Look Darth, bet you wouldn't hit a guy with glasses
When Vader strikes Ben down? To the audience it comes across as a cold-blooded murder. Ben stands there defenseless, having given himself up. It makes Vader seem that much more sinister to the audience to have killed an opponent who has effectively surrendered. While there's clearly more to the story, we're talking about audience perception in the moment. We don't know until much later that Vader played into Obi-Wan's hands, and that Obi-Wan had been preparing himself for a moment like that for nearly 20 years.
Again, this is not done to the effect they wanted. First off, Vader's first on screen action is the brutal strangulation murder of a prisoner who is absolutely no threat to him. Vader is established right away as the most sinister, remorseless, unscrupulous villain we might ever meet. That's why we **** a brick when Ben turns the corner to the hangar and sees Vader looming there. We know the guy is going to pull no punches, he's been yammering to Tarkin for the last half hour how much he wants to kill Kenobi. And by God we know he's got it in him to do it.
If they wanted Vader to come across more threatening because of Ben's sacrifice, then instead of him poking around to see where Ben Kenobi went, he should have crossed his arms and sneered something like "Foolish old man!" or something to that effect. His reaction to the duel's end is that he has been tricked. He does not appear satisfied, and I think that actually lessens