Rogue One’s Vader is the kind of Vader I expect in the timeline closer to RotS. It’s too jarring to see nimble Vader so close to ANH. But I mean, I wouldn’t mind a Vader film around that timeline, hunting Jedi.
Using one handed blade work isn’t being nimble; jumping all over the place and running swiftly is being nimble as far as the dictionary is concerned.
You’re right.
Fluid would be the better word.
I would probably agree with you if we had a scene of slaughtering Rebels in the OT. Such a scene would have been shot in a completely different from the Vader vs Ben duel for a myriad of reasons. The most pertinent of which is that you don’t have to develop the choreography around Sir Alec Guinness.