system
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human
[Star Wars] How good of a duelist was Luke Skywalker after his training with Yoda?

I just noticed that at one point in the exchange before he gets his hand chopped off that he actually lands a blow on Vader, and like a nice solid hit that if not for whatever armor the Dark Lord has on probably would have taken  the limb off. Now at this point Luke hasn't ever been shown to have any specific lightsaber training aside from his crash course with the Remote on the Millennium Falcon before the Death Star encounter, it never seemed like Yoda trained him for it instead more concerned with actual force stuff. To top it all off we have Cal Kestis who we saw was a fairly competent duelist for an amateur defeating two separate inquisitors and chopping his way through dozens of enemies without a single blaster, not to mention some unspecified amount of action he might have potentially seen in the Clone Wars (although given his age we don't know if he ever participated in any actual fighting) and when he fought Darth Vader he didn't even get the health bar only managing a single (if gruesome) blow on Vader with the help of BB8 tazing him. So does that mean that Luke is a better duelist than Cal was?
gpt
Yoda has had twenty years to think up a lesson plan, on top of his (probably) century+ of teaching experience already, and he's working with a student with a tremendous amount of natural potential, so it isn't absurd that Luke is much better than the average Jedi would be after just a few weeks.

The major difference here is that Vader is explicitly not trying to kill Luke, and isn't taking him that seriously, while he couldn't care less about Cal. When Luke scores his glancing blow on Vader, that's likely the first time Vader considers this a serious exercise, and Luke is disarmed, missing a sword hand, and totally at Vader's mercy just a few seconds later.