Many viewers have pointed out that Thanos was able to lift Stormbreaker without a problem, but this is because the ax isn't enchanted as Mjolnir is. Others believe Thanos lifted Mjolnir (although briefly) and have even argued that he would be worthy of doing so.
It is NOT enchanted. Most people make this mistake but it was confirmed by the directors that anyone who possesses the ''physical strength'' to lift the weapon can lift it. How was Thanos able to lift both Mjölnir and Stormbreaker? He was able to lift Stormbreaker because Stormbreaker is purely about strength.
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. This applies to your last two questions as well. If you can lift Mjolnir, you can wield it.
Thanos did not know what the weapon was capable of, instead he thought blasting it would either stop it or disintegrate/break it. We can clearly see that Stormbreaker absorbs all the energy thrown at it and discharges it as it strikes Thanos.
How Can Thanos LIFT Stormbreaker? Avengers Endgame Explained - Stormbreaker vs Mjolnir
Is Thor's Axe stronger than Thanos?
In need of a new weapon after the events of Thor: Ragnarok, Thor used the Dwarven forge on Nidavellir to craft Stormbreaker. Due to both the nature of the weapon and Thor's attack on Thanos, Stormbreaker successfully powered through an energy blast from all six stones and dealt a near-lethal blow to Thanos.
It is safe to say that Stormbreaker cannot be destroyed by anything audiences have seen in the MCU so far. A power that Stormbreaker lacks is the "worthiness" enchantment of Odin. Anyone physically strong enough to lift and use Stormbreaker can use it.
However, Thanos is still standing, and he forces Odin to unleash the full might of his power, the Odinforce. In an epic sequence, Thanos keeps advancing toward his foe, withstanding blast after blast of deadly energy. In the end, Odin is too strong, and Thanos is clearly beaten.
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.
There's a chance it could be repaired -- after all, Mjolnir has been broken and remade on multiple occasions -- but seeing Thor break Stormbreaker willingly is still a shocking sight. By destroying Stormbreaker, Thor not only reaffirms how powerful he is, but he also shows Bill how determined he is in his new quest.
He traveled to Nidavellir and forged Stormbreaker, a weapon not only strong enough to kill Thanos but counter the Infinity Gauntlet and even summon the Bifrost. However, the weapon wasn't ready until Groot completed it by dismembering himself - and, in doing so, he became the first person to lift Stormbreaker.
Meanwhile, MCU Phase 4 saw Stormbreaker being wielded by Thor, Gorr the God Butcher, Love, and anyone else who was strong enough to actually lift and swing it. This is because of the respective origins of both legendary Asgardian weapons.
Thor's hammer Mjolnir was defined by the fact that only the 'worthy' could lift it – so basically no-one except the god of thunder (and Vision, for some reason). But when it comes to the weapon's replacement, Stormbreaker – which Thor forges in Avengers: Infinity War – Groot is able to lift it too.
As mighty as they are, neither Thanos nor Superman is immortal. Both have been killed in the past, meaning neither is unbeatable. However, Thanos would need an ironclad plan to trap and defeat the Man of Steel, because if it comes down to plain old fisticuffs, Superman is definitely going to win.
If Marvel fans have ever wondered if Spider-Man was worthy of lifting Thor's hammer, the answer is yes. Just NOT the Spider-Man you think… Although he didn't really meet Thor beyond a couple shared scenes in Avenger's Endgame, Spider-Man has shown he's actually a big fan of the Thunder God.
Although vibranium is susceptible to damage, it's depicted as the most durable material in the Marvel Cinematic Universe. The fact that Thanos possesses enough power to beak vibranium is a testament to the strength of the Mad Titan, but more importantly, the weapon itself.
Due to it being composed of Uru, the weapon is nigh-indestructible and able to withstand energy blasts created by the Infinity Stones. It is also able to channel dimensional energy and summon the Bifrost Bridge, which enabled Thor to teleport himself, Rocket Raccoon, and Groot to Wakanda.
Mjolnir doesn't damage Cap's shield at all, as shown below. I think it is fairly safe to assume that Stormbreaker (being a cutting weapon, rather than Mjolnir which is designed to smash or build) would inflict similar damage to the shield as Thanos sword does. Conclusion: Stormbreaker minces Cap's shield.
Rune King Thor is perhaps the strongest version of Thor we have ever witnessed in the Marvel Comics. In the desperate need of power, Thor makes the ultimate sacrifice of his life in the Mighty Thor #80–85. He hangs himself from the tree of Yggdrasil to get his hands on Rune Magic and he literally died.
Only with the power of the Infinity Stones does Thanos stand a chance of beating Galactus in a fight; it's fortunate for him (and for the universe) that Galactus considers himself above such moral concepts as good and evil, choosing instead to eat planets out of a desire to satiate his hunger rather than a desire to ...
He transported Thor back to Asgard where Odin took this as an act of war and fought an extremely destructive battle with Thanos. Even upon learning the truth, Odin did not thank Thanos for his reluctant altruism, but told him to leave and never return.
While Zeus is by no means a pushover, unless he has some immensely powerful tricks up his sleeve in Thor: Love and Thunder, it appears that the MCU's Odin is still the strongest god on the cosmic block.
So, while Stormbreaker grows roots in Thor: Love and Thunder, it is not another Groot being grown but an extension of a plant with the feelings of a teenager. Stormbreaker's jealousy comes from being born of a teenage Groot, and that's why it's so anthropomorphized in the film.
While Superman could potentially overpower Thor, blows rendered by the mystical Mjolnir would likely impose serious damage on the Kryptonian hero. However, with his super-speed, the Man of Steel could probably avoid the Thunder God's lightning.
And Mathaudhu can cite documentary sources to back him up. For example, Marvel – which publishes the Thor comics – issued a “Thor's Hammer” trading card in 1991 that states Mjolnir is made of Uru and weighs precisely 42.3 pounds. That's lighter than a herd of 300 billion mice, much less a herd of 300 billion elephants.
