Avengers: Infinity War depicted Thor (Chris Hemsworth) using Stormbreaker to (almost) best Thanos (Josh Brolin) in their rematch; but the powerful ax might have another purpose beyond defeating the Mad Titan.
The hammer Mjolnir has been a key part of Thor’s iconography ever since his beginnings in Norse mythology. But whilst Marvel’s comics – and the Marvel Cinematic Universe – have long reflected this attachment, the God of Thunder has not always wielded this famous hammer. In Marvel’s ever-growing canon, other characters like Beta Ray Bill have wielded Mjolnir, and Thor has used alternative armaments from time to time. In this way, Infinity War mimicked Thor’s swapping of weaponry in his comics through the debut of Stormbreaker.
Having lost his beloved hammer in Thor: Ragnarok, Thor sought a new weapon to enact his vengeance against Thanos in Infinity War. Indeed, his efforts to acquire Stormbreaker were immediately justified by its subsequent performance. With the new ax in hand, Thor almost single-handedly decimated Thanos’ forces in the Battle of Wakanda and, in the movie’s most pivotal scenes, came closest to killing Thanos himself. Though Stormbreaker has already proved popular with fans, some critics felt that the presence of the blade undermined Thor’s wider character arc. Yet rather than hampering Thor’s story, Stormbreaker may be correcting it by returning abilities that he had lost.
As is the case with many of Asgard’s famous weapons, Mjolnir and Stormbreaker were created by the dwarf king Eitri (Peter Dinklage) in the realm of Nidavellir. Though the MCU never specifies what Asgardian armaments are made of, they are likely made out the same fictional element as the comics: Uru, a massively resilient metal that both absorbs and manipulates magical energy.
Since its first appearance in the MCU, Mjolnir has exemplified these qualities. The hammer seemingly served as the source of Thor’s lightning powers (more on that later) and allowed him to fly at great speed. Certainly, it proved to be a formidable asset in all of Thor’s appearances, when its power waylaid huge swathes of Ice Giant, Chitauri, Dark Elf armies, and more. Mjolnir’s enchantment of worthiness also benefited Thor, since it meant that few other beings could wield or move it. Certainly, the fact that the Vision (Paul Bettany) was able to lift the hammer meant that Thor and his teammates could immediately recognize the purity of synthezoid’s heart in Avengers: Age of Ultron. But two years later, Thor confronted Hela (Cate Blanchett) the Goddess of Death in Thor: Ragnarok where, in their first encounter, she promptly destroyed the hammer with her bare hands.
Though Thor eventually bested Hela without his hammer, he was soundly beaten by Thanos within the first few minutes of Infinity War. After being rescued by the Guardians of the Galaxy, Thor asserts that he needs a new weapon, and he travels with Rocket and Groot to procure one. They encounter Eitri – the last of his people to survive Thanos’ wrath – and together they forge the “King’s weapon” Stormbreaker. This new ax is supposedly the most powerful in Asgard’s history. It not only summons the Bifrost, it also negates the combined power of the Infinity Stones.
Prior to Stormbreaker’s debut, the loss of Mjolnir was a fitting development for Thor. As the MCU has expanded, Thor had become more knowledgeable about his realm’s dark past, and attempted to become a better, more responsible ruler. As such, the acquisition of Stormbreaker was viewed as being contrary to these plot points. Indeed, Thor’s journey to Nidavellir has been perceived as Marvel simply wanting the God of Thunder to have a weapon again, or else giving him something to do in Infinity War’s extended run-time. However, whilst Stormbreaker may be those things, a key detail in Thor: Ragnarok suggests that Thor’s ax fulfills an in-world necessity.