After the unprecedented success of A New Hope and The Empire Strikes Back, fans were eager to see how George Lucas would wrap up his Star Wars trilogy. Then, as Return of the Jedi opened, fans were concerned to see that Luke was wearing dark robes, indicating that he might have fallen into darkness after learning that Darth Vader was his father. However, that notion was quickly dispelled when he announced to Jabba the Hutt that he was a Jedi Knight. Shortly after, he proved his mettle when he revealed his brand-new lightsaber and helped rescue Han Solo.
Source：https://www.cbr.com/star-wars-return-of-the-jedi-vader-luke-skywalker-lightsaber/
