Mjolnir is a connection to Thor as he is pre-Infinity War, still finding his footing as a hero and learning how to find power within his relationships instead of within his physical ability. In this sense, Mjolnir is almost like a best friend to Thor.
Like Stormbreaker, Mjolnir also allows Thor to wield thunder and lightning; however, it's not capable of summoning the Bifrost. The magic hammer did develop a power Stormbreaker couldn't, though, and it's able to detach its broken pieces to attack multiple enemies at once, before coming together again.
It seems Thor enjoys both weapons; after all, he seemed very happy to find out he was still worthy in Avengers: Endgame. But as mentioned before, it appears that he prefers Stormbreaker out of the two, and rightfully so, because it gives him the best advantage over his enemies - in ways that Mjolnir doesn't.
Is Thor still worthy in Thor: Love and Thunder? It is pretty clear that Mjolnir chose Jane, not because Thor was unworthy, but because Thor's oath had instructed it do so. Sadly, the hammer cannot cure Jane's cancer, and can only transform and temporarily empower her.
The fact that Thor doesn't have to think about risking his life to save Sif or Freyja shows that doing so is a reflection of who he has become—and that person (or god) can truly be said to be worthy.
Other Marvel characters have lifted Mjolnir not through worthiness but through technicalities such as absorbing Thor's powers, including the Air-Walker, Awesome Android, Magneto, Rogue, Wonder Man, and Doctor Doom.
However, the film also implies that the hammer only sees Jane as worthy because Thor unintentionally revised the rules of Mjölnir, giving it the power to protect her. Captain America didn't need anything special for the hammer to see him as worthy – he's able to wield it without issue in Avengers: Endgame.
Thor Odinson initially suspects Jane might be this new hero. But he eliminates her from his list of suspects because she is going through chemotherapy for breast cancer, which, he reasons, would make her too weak to fight.
Yes, even Spider-Man has been worthy of holding the hammer of Thor. This is not your father's Spider-Man (well, actually, it could be if your dad was a kid in 1993), but instead is the Spider-Man of Marvel's distant future of 2099!
Originally there was no restriction placed on the hammer for who can use it but after Thor's reckless behavior, Odin Borson placed an enchantment on it. This spell read "Whosoever holds this hammer, if he be worthy, shall possess the power of Thor." Only those deemed worthy to lift Mjolnir can.
In Thor #21, the being inside of Mjolnir lashed out at Thor, and the reason makes it seem like Thor's angry ex. This changes everything about Marvel's history, and it could also impact the MCU.
Stormbreaker is jealous about Mjölnir's return because the ax is basically a moody teenager.
Hence, Mjolnir determines worthiness based on Odin's definition of worthiness. However, since Mjolnir also has a conscious being within it, in the form of God Tempest, another likely explanation is that it is God Tempest that determines the worthiness.
Why is this such a big deal? Well, for starters, the hammer in question, Mjolnir, can only be wielded by those who are considered “worthy,” a little mystical insurance policy put on it by Thor's dad, Odin. It's pretty cool to see the Avenger who is the purest of heart officially deemed “worthy” of the weapon of a god.
The movie doesn't explain Thor's motivations for giving up Stormbreaker, but it makes sense that Chris Hemsworth simply wanted Love to have a powerful weapon to aid her in battle. It's unlikely that he could give her Mjolnir, considering that so few people in the MCU have been deemed worthy of its power.
Stormbreaker can be used by anyone, it isn't bound by Odin's enchantments to only be lifted by the worthy. Mjolnir is, however, still enchanted, meaning that only those that are worthy may wield it.
Venom Is Truly Worthy.
This is by far the most simple explanation, as it is in keeping with how Mjolnir has been used by other heroes besides Thor and Odin over the years.
Forged by dwarves in the heart of a dying star, the weapon is enchanted so that it can only be lifted and wielded by those who are worthy of its powers. Both in the comics and the MCU films, many characters other than Thor himself, both heroes and villains, have been able to lift Mjolnir.
Yes, as a shock to many, Superman has briefly lifted the mighty hammer in a phenomenal crossover with Marvel and DC Comics.
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.
During the events of Thor: Ragnarok, Hela (Cate Blanchett) shatters Mjölnir into dozens of small pieces. In Love and Thunder, we learn that all the pieces of Mjölnir are kept in New Asgard, as a touristic attraction to those who wish to see the God of Thunder weapon.
Years later, Mjolnir reforged itself for Jane Foster, transforming her into the Mighty Thor. It was able to stave off her stage 4 cancer, but weakened her mortal form's ability to stave the cancer off every time she harnessed the hammer's abilities. After she finally succumbed to her cancer, Thor reclaimed the hammer.
One possibility is the simplest one available, which would hinge on the rules put on the hammer by Odin's enchantment, which are “Whoever holds this hammer, if he be worthy, shall possess the power of Thor.” Jane was able to take Thor's place in the comics because she became worthy enough to wield Mjolnir, so if the ...
It is revealed that Thor and Jane broke up sometime after the events of Avengers: Age of Ultron. When a fangirl tells Thor she's sorry that Jane dumped him, he sheepishly replies that it was a mutual breakup.
Thor: Love and Thunder, even though it was released in the summer and played in theaters up until its Disney+ release, left fans displeased and unsatisfied, angry about not living up to expectations, its use (or, more correctly, misuse) of characters, and humor that didn't land.