GREAT question!!! :D Here are some excerpts from an artikulo on Wookieepedia that specifically addresses your question.
1. What is the essence of Force Deflection?
Answer: Force Deflection was a Force power used sa pamamagitan ng Jedi and Sith who were without a lightsaber, or chose not to carry one. It is unknown exactly if the Jedi and Sith merely created a pader using the Force to deflect blaster bolts, and Energy, or if they actually deflected them back with their hand. It took much skill in the Force to use this, however, and most Jedi used their lightsabers instead to deflect incoming attacks.
2. Who used/possibly used Force Deflection to block/deflect energy or blasts in bituin Wars. (Notice that energy is a vague term; even scientists cannot tell us what the actual nitty-gritty composition/essence of energy is. For example: "Energy is the ability or capacity to do work or to produce change." Well, that only states WHAT energy stimulates, not what it actually is. It stimulates the capacity to work or produce change. Just a little side note there for scientific thought :) ) ANYWAYS...lol back to examples of deflecting energy, blasts, or projectiles in bituin Wars
A. Grand Master Yoda used deflection to block barrages of Force lightning hurled at him while dueling Darth Tyranus, and again when dueling Darth Sidious. It is possible that Yoda combined Force Deflection with Force Absorb when protecting himself against Force lightning. He was unsuccessful against Sidious because he was trying to gather the lightning's energy into an orb to apoy back at Sidious, but it overloaded and exploded, throwing the combatants apart.
B. When Luke Skywalker dueled his father, Darth Vader, in the Temple of Pomojema on Mimban, Vader fired a ball of kinetic energy at Luke. Luke was able to use this power and redirect it towards the Sith Lord, even though he had little training with Obi-Wan Kenobi.
C. (This is the one you referenced)
Darth Vader may have used this ability to deflect blaster apoy from Han Solo in ulap City. However, the shots may have been deflected sa pamamagitan ng his armored mechanical hand, rather than the Force, so whether he did use this power is debatable. However, Luke Skywalker believed that in this incident, Vader used the ability known as Force Absorb to absorb the incoming fire, and redirected the energy thus absorbed to pull the blaster out of Solo's hand.
So, as you can see, the topic is "debatable," meaning that George Lucas did not give us a solid answer. It could be that Vader used Force Absorb to literally absorb the blasts, or he could have constructed a "Force wall" in order to repel the blasts. In my opinion, I believe he used Force Absorb, but if he speculated ahead of time that Han would apoy at him, then he would've been prepared to create a pader of defense using the Force in a very limited amount of time. I hope this helped you out!
P.S.: Here is the link to the full article:
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