Here is a good question: If Force users could block Blaster fire with thier hands or "The force" why would they need to use a lightsaber to block blaster fire?
Yes, Yoda was able to block and absorb Force lightning. But Blaster fire is much differant.
IMHO it was likely a combination of Vaders armor AND force powers. It was one of those "neat tricks" that he learned likely when he went on to Exterminate the surviving Jedi after RotS.
Yes there are some EU and video games that would say different. But even some Jedi Masters still blocked blaster fire with sabers and not their hands
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