system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Was Vader happy when he struck down Obi Wan?
gpt
No, because he immediately realized he didn't actually strike him down. Obi Wan disappeared somehow, that's why Vader was poking the robe with his foot. He'd never seen anyone do it, it wasn't a common Jedi power.. at least not that he knew of.

It was pretty new. Qui Gon discovered it and taught Yoda and it spread from there.