“For those of you who haven’t seen Avengers: Age of Ultron in a while, one of the standout moments of the film is Vision casually lifting Thor’s hammer when he’s first created, then outright wielding it later during the fight in Sokovia. At the end of the film, Steve and Tony are arguing with Thor about how he pulled it off. Their two theories are that either 1) as a machine, Vision doesn’t count as a living being and can lift the hammer like an ‘elevator’ could lift it, or 2) Vision’s a genuinely pure soul who — as a being on ‘the side of life’ — is worthy of protecting the human race.
Vision’s up there with my favorite Avengers, so I’m sorry to do him dirty like this, but…my theory is that Avengers: Endgame kind of implies that the ‘machine’ theory was the right one all along and only Thor and Steve are truly worthy.
Steve lifts the hammer during the final battle. Like Vision, he can call the hammer to him and swing it around — but UNLIKE Vision, he can actually summon lightning, and uses that as part of his attacks. Now, remember the inscription on the hammer:
‘Whosoever holds this hammer, if he be worthy, shall possess the power of Thor.’
Thor’s power is lightning. It’s not being able to lift the hammer. When Thor uses his power, the hammer works as a conduit for that. He doesn’t get the lightning FROM the hammer itself and Thor: Ragnarok establishes that. The lightning is the power of Thor, and the lightning is what Steve can use — whereas Vision can’t.”