I can somehow see the point of casting an experienced actor (instead of David Prowse) for the end of Return of the Jedi and I have to say that Sebastian Shaw’s performance of Anakin’s death was really great.
From my point of view however, 78-year-old Sebastian Shaw seemed like a weird choice for the character even back then in 1983.
Since ANH it was established that Darth Vader was a “young Jedi” and a pupil of Obi-Wan until he turned to the dark side. In the same movie, we hear Vader calling Obi-Wan an “old man” during their lightsaber duel.
I know that Vader and Luke’s father were still separate characters at this point of time.
Luke’s father was probably meant to be more or less the same age as Obi-Wan.
In TESB, both characters were merged into one and Luke’s father Anakin suddenly became “the young apprentice of Obi-Wan who turned to evil”.
So, I basically imagined a Jedi who was in his 20s (like Hayden Christensen) or early 30s when he became a Sith and fathered Luke and Leia but Shaw looks noticeably older than that (more like a guy who became a father in his 40s).
Furthermore, I think that Shaw didn’t really look menacing or “dark” enough for Anakin Skywalker.
When I saw the unmasking scene, my first thought was: “This friendly grandpa was Darth Vader, one of the most feared villains in the galaxy? Really?”
What do you think?