Star Wars Episode 1: The Phantom Menace - Twirling Lightsaber
During the Jedi vs. Sith battle, Darth Maul uses the force to move debris to open the door, look to the left.(wide screen only) You will see Obi-Wan carelessly twirling his lightsaber and walking toward the door as if the were no battle at all. Yeah, nice. Could've killed the sith lord if he wasn't so busy playing around with his lightsaber.
I saw this the first time I saw it and it is easily explained. Maul was backing off and Obi-wan was already exhausted (it says so in the book) and he was taking a quick breather and loosening his wrist.
I kinda agree with the wrist loosening bit, but if you watch all of Ol' Ben's fight sequences he's 'loosening his wrist' in every other scene. He does his little wrist twirl more times than Ani-boy say "Oops". In the final Jedi vs. Sith duel, he does the twirl 8 times, twice while running down the power coupling corridor. Did he have premature arthritis or something?
The wrist flip with the sword is almost like a natural occurrance. If you have ever picked up a sword of proper weight and balance, the natural thing to do is to flip it around. Also if you have any knowledge of fighting of any kind you would know that it is best to always keep your body moving, you can react quicker that way. Spinning is the best constant movement i can think of with a sword.
Lightsabers don't have a weight and balance. The blade is made out of energy and cannot possibly have any weight. The actors used thin sticks that did have weight and could be twirled to establish a balance to the blade. It would seem that's the reason you need to be a Jedi to actually be able to fight with one. Try "twirling" a lightsaber replica without the blade extended. Not exactly the easiest thing to do.
From the Star Wars Attack of the Clones Visual Dictionary: A Shun is a "One handed grip, spinning lightsabre 360 degrees to gain speed for an attack." It is a recognized move taught to Jedi in lightsabre training.