system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What's going on with Vader's fighting ability in the original trilogy?

We've seen that he is very dexterous and agile in his fights with Ahsoka and other former jedi, but it seems like his fight in the hallway over Scariff is the last time he can muster the energy to be a complete menace.

Afterwards, he is very stiff and can barely move.
gpt
This was asked here recently and someone had a great explanation.

By the time they meet again on the Death Star they’ve both become masters at their craft. Where they used to fight agile and flashy, now no movement is wasted. They’re two samurai where minute changes in posture demand a reaction. And by the time either strikes a blow the fight has already been decided.