I don’t know anything about fencing or swordfighting, but I’m sure somebody on the SDMB was on the college fencing team or is one of those Medieval Faire types and could respond to this. Specifically I wonder about:
The Adventures of Robin Hood: Errol Flynn is fast as lightning, but he has this habit of twirling his sword over his head when he’s fighting off a bunch of guys at once. Whatever works, I guess, but does this look weird to you?
Star Wars: Should Obi-wan spin around in his big fight with Darth Vader? Is it okay to even momentarily have your back to your enemy?
The Princess Bride: Okay, they were certainly camping it up here, but in the big swordfight scene between Inigo and the Man in Black, they’re both supposed to be the best of the best swordfighters, and Inigo is tremendously impressed by the DPR’s skill. They also refer to different maneuvers by name – is this legit?
Any incarnation of The Three Musketeers: Thwack! Thwack! ching! They always seem slow and showy to me – lots of arm movements. You’re trying to kill somebody! Get on with it!
Granted, it’s show biz, and you’ve got actors who’ve been learning to do this for about three weeks trying to look as if they’ve been actually doing it for years. Any screen sword performances you especially admire?