When this scene originally played out in May 1977, movieogers knew very little about lightsabers and how they work. At that point in the Star Wars saga, we had only seen a lightsaber used once- when Kenobi defends Luke in the cantina in Mos Eisley. When Vader swipes at Kenobi and an empty cloak falls to the deck, I assumed that Vader's lightsaber had cut Kenobi in half and vaporized him.
In the episodes that followed, Lucas revealed more about the Jedi and their lightsabers:
- You cannot vaporize someone by cutting them in half (see Darth Maul, Episode 1).
- Jedi's bodies can disappear when they die (see Yoda, Episode 6).
- Jedi's bodies don't necessarily disappear when they die (see Qui-Gonn Jinn, Episode 1).
My problem is that none of this is obvious from the way Lucas staged it in the movie. I would have staged it like this:
The old Jedi Knight looks over his shoulder at Luke, lifts his sword from Vader's, then closes his eyes with a serene look on his face. Vader brings his sword down, mortally wounding Kenobi. Ben falls to the deck. Vader looks down on Kenobi's dead body as his form fades away to nothingness, leaving only his cloak and lightsaber behind. Vader is puzzled at Ben's disappearance and pokes at the empty cloak.Not only would this effect have been easier to create with optical effects, but it would have conveyed the idea better: Vader kills Kenobi with his lightsaber, and then Kenobi passes on to the afterlife.