If Lucas had the “Vader is Luke’s father” thing planned that early, he didn’t tell anyone. I read the novelization (attributed to Lucas, actually written by Alan Dean Foster) many times back then, until the cover was literally falling off. Right before Obi-Wan tells Luke that Vader killed his father, the narration says, “Unlike Owen Lars, Kenobi could not take refuge in a comfortable lie.” So Foster certainly thought that Obi-Wan was telling the truth, and that Vader and Anakin were two different people.
Likewise, the first draft of the script of Empire Strikes Back, written by Leigh Brackett, has Anakin appearing to Luke on Dagobah as a force ghost, along with Obi-Wan. So Brackett also thought that Vader and Anakin were two different people. It seems strange that Lucas wouldn’t have told the person he hired to write the script about such an important plot twist.
Much more likely is that Lucas hadn’t thought of it yet, and the idea of Vader being Luke’s father was developed during the writing of Empire.
That’s an exhaustive article on Wiki about the light saber. I have only seen the first 3 movies so I had not seen any of the light saber variants from the later films. Even the name “light saber” is perfect! I can’t think of any other description that conveys the elegance of the weapon. Has there ever been another fictional weapon that has so much thought and development?
Yeah one takes it for granted after all these years but “lightsaber” is a great name. And there was indeed a lot of thought packed into a single weapon, not least the whole “lightsaber versus blaster” theme which Lucas borrowed from Kurosawa and ultimately samurai history.
