Thanos’ sword in Avengers: Endgame may be another creation of Eitri (Peter Dinklage) and Nidavellir. The Marvel Cinematic Universe has had no shortage of powerful weapons and artifacts over the last 11 years. There’s been Captain America’s vibranium shield, Mjolnir, the Infinity Stones, and much more. But, the last two Avengers films have introduced some of the strongest ones yet.
Avengers: Infinity War saw Nidavellir create the Infinity Gauntlet and Stormbreaker. Thanos used the gauntlet to wield all six Infinity Stones and wipe out half of all life across the universe. Meanwhile, Thor had Eitri make Stormbreaker as a «Thanos-killing» type of weapon, and it proved to be more powerful than a completed gauntlet. Avengers: Endgame made good on the purpose of Stormbreaker too, as Thor used it to chop off Thanos’ head. Thanks to time travel, though, a warrior-version of Thanos from 2014 returned to the story and brought with him a mighty sword. It was powerful enough to withstand Stormbreaker and break Cap’s shield.
These acts left many viewers wondering what Thanos’ sword could be made of and where it originated from. Now that Avengers: Endgame is available digitally, a possible answer may exist. The audio commentary track with director Anthony and Joe Russo and writers Christopher Markus and Stephen McFeely included them talking about the power of Thanos’ sword as he broke Cap’s shield. They don’t directly confirm its origin, but Joe does tease that Eitri could be the answer.
Markus: While vibranium is the strongest substance on Earth, whatever Thanos’ straight razor there is made out of is stronger.
Joe Russo: Well Thanos clearly knew Eitri.
This tease could be an indication that this is where the Russos believe the sword came from, but what is in Avengers: Endgame and this quote are not a confirmation. It will take future films or details to prove this to be true or not, with Marvel Studios still holding the ability as of this moment to have a different explanation than Joe Russo’s. With what Avengers: Endgame showed the sword capable of, though, it originating from the place known for making the most potent weapons in the universe does make sense.
If it is later confirmed that Eitri and Nidavellir created Thanos’ unnamed sword, then it will further live up to its legend. Nidavellir would be the birthplace of Mjolnir, Stormbreaker, the Infinity Gauntlet, and Thanos’ sword, and those are just the weapons we know about. We’ve previously theorized that Ronan’s hammer could be another creation of Nidavellir potentially.
However, there are also exciting possibilities in store if Marvel opts not to make the sword come from Eitri. Some have speculated that the metal could be retconned as adamantium and the portion of the sword that broke off could be used to give the MCU’s Wolverine his indestructible claws. One of our theories is that the Celestials created the weapon, something that could be explained in Eternals. In any case, it appears the Russos think Eitri is the one responsible for Thanos’ sword from Avengers: Endgame and now it’s up to Marvel Studios to confirm it.