I remember when Darth Vader chopped off Luke Skywalker's hand in Empire Strikes Back, it was shocking. But it seems Vader was only following tradition. After seeing the new movies, it seems that there are only two ways to end a lightsaber fight. One, of course, is to kill your opponent. Obi-Wan vs Maul. Qui-Gon vs Maul. The other is to chop off their hand.
Think about it. Vader vs Luke. Anakin vs Dooku. Dooku vs Anakin. Obi-Wan vs Grievous. All ended by chopping off the loser's hand. Or hands in the case of General Grievous and Count Dooku. I guess Dooku was ambidextrous. It makes sense. If they have no hand, they can't fight. But every time? They must have a class on that in Jedi school. "Okay, if you can't kill your opponent, chop off their hand. Right there. Below the elbow." You'd think after centuries of battle, the Jedi or Sith would have developed some sort of wrist armor to keep that from happening.
The only two exceptions were Darth Sidious vs Maul and Obi-Wan vs Dooku. It always struck me as odd when Dooku cut Obi-Wan's arm and leg without slicing them off. He just nicked Obi-Wan. Maybe he didn't have the heart because they were old friends, but that seems unlikely. A few seconds later, Dooku was getting ready to chop Obi-Wan's head off. And Obi-Wan didn't hesitate to slice off his "brother" Anakin's arms and legs. The real reason Dooku didn't hack them off, of course, is that Obi-Wan had to have his hands for the rest of the series. Lucas kind of backed himself into a corner with that duel, and the paper-cuts were his way out.
As for Darth Sidious, he is the only person in the entire series who ever lost a duel without getting his hand cut off. He just dropped his lightsaber. Either that's because he is the worst lightsaber fighter in the history of the Force or he was the smartest. He knew he couldn't beat Windu and wanted to keep his life and his hands, and knew if he held onto the saber, he would lose one or the other. Besides, he knew he could fall back on the lightning.
Note: Turns out there really is Jedi training on chopping off someone's hand. It's called cho mai as in "You cho' off mai hand!" Just kidding.
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