Thor essentially 'gives birth' to Vision, which means there's part of him – or more specifically part of Mjölnir – in Vision, which gives him the ability.
The strongest, most logical theory why Vision can lift it with relative easy is due to the fact he is created with an Infinity Stone – the one found within the gem of Loki's scepter.
But before they got a chance to settle, Thanos' henchman Corvus Glaive arrived and pierced Vision's chest with his blade. Since Vision was caught off-guard, he didn't have time to phase through the blade, and his synthezoid body began to malfunction.
We Now Know Why Cap Didn't Lift Mjolnir In Age Of Ultron
Could Vision beat Thanos?
This alternate has an argument, and perhaps the Thanos of its universe was somehow inherently weaker than the core MCU's, but there doesn't seem to be any scenario where the Sacred Timeline's Vision could ever defeat its Thanos, who had already harnessed five of the six Infinity Stones.
Clearly, Thanos is aware he wouldn't be able to lift it. Although it's hard to pinpoint what exactly makes someone worthy of using Mjolnir, as it's ultimately determined by Odin, who placed the enchantment on the hammer, some believe one's worthiness is measured by traits like courage, honor, and selflessness.
It turns out the secret he was keeping about Tony Stark's parents – that Bucky (Sebastian Stan) was behind their deaths –was weighing on his mind, making him “not completely worthy” of wielding it.
Meanwhile, Christopher Markus and Stephen McFeely say that Steve Rogers was genuinely unable to lift the hammer as he was still being held back by lying to Iron Man about Bucky Barnes killing his parents.
In the end, Deadpool wasn't worthy. While he seemingly had control of Mjolnir and the strength of Thor, it was all a mirage put on by Loki to distract Thor.
While Batman does have some of the characteristics that would allow him to lift Mjolnir, he also has committed several acts that disqualify him. This is a man who once kept extensive files on his allies in case he needed to take them down, files that were stolen and used against said allies.
The hammer Stormbreaker is very similar to Mjolnir, made of mystic Uru metal and is nearly indestructible. Worthiness: Just like the original Mjolnir, no one can lift Stormbreaker who is not worthy. After the founding of New Korbin, there was a line of aliens and Korbinites all attempting to lift Stormbreaker.
Vision may have technically been a child, but he understood what The Avengers represented, as well as the concept of heroes. While he could've emulated any of the surrounding others, he possibly chose Thor because he represented, in its purest form, what a hero was supposed to look like.
The Vision is quite strong as well - he can rip straight through a mutant-hunting Sentinel's armor - but not nearly as strong as Thor. The Vision's only hope in winning this battle rests with his unique ability to control his body's density.
The simple answer is no. Yes, Hulk absolutely smashes Thor to the ground with Mjolnir, but, he's holding both Thor and the hammer. Hulk wouldn't have been able to lift Mjolnir by himself, but since the God of Thunder had a firm grip on it as well, he was able to use it as a weapon against his teammate.
Stormbreaker has the additional power to summon the Bifröst, allowing Thor to teleport anywhere in the Nine Realms. Screen Rant has identified Stormbreaker as the more powerful of the two, based on this ability, as well as it being a much larger and edged weapon.
Aside from Thor being aware of Captain America's worthiness, the MCU set his amazing scene from Avengers: Endgame up throughout Steve's journey. The first installment featuring Steve, Captain America: The First Avenger solidified one of the main reasons why he was worthy of Mjolnir in the end: he was simply a good man.
Could Thor have beaten Thanos by himself if he was fit in Endgame? Yes. Thor at his peak could have beaten Thanos by himself. One hit from him using Stormbreaker would mortally wound Thanos.
But as it turns out, it was not just Thor's strength. After all, no weapon in existence should be able to stop the combined power of the Infinity Stones, no matter how powerful the wielder is. Turns out, Thanos was taken unawares. He had just incapacitated all the heroes who tried to stop him.
He simply wanted him dead at all costs because he was his biggest threat. As per the user, the director of Avengers confirmed that Thanos was most scared of Iron Man. “Not because of his strength, not because of his power, not because of his power, but because of his suit,” he added.
It can absorb and block energy attacks as well as penetrate vibranium—which Corvus does when he stabs Vision, twice, in the chest. Though neither blow kills Vision, the subsequent wound severely incapacitates the living android, taking away his ability to phase or recover easily.
With what seemed to be his last bit of strength, Thanos, much to Thor's horror, snapped his fingers to activate the Infinity Gauntlet and passed out. He awakened in the Soulworld where he found a younger Gamora, who asked him if he completed his mission. He solemnly replied he had.
