Thor: Ragarok saw Thor's signature weapon Mjolnir smashed into itty bitty pieces, and we were shocked to see he didn't find a replacement by the time the movie ended. Thanks to a leaked image of a Lego set though, we may have a hint at Thor's weapon against Thanos for Avengers: Infinity War.
Check it out:
The axe between Groot and Thor look very reminiscent of Jarnbjorn. In The Mighty Thor comics, before he was able to lift Mjolnir, young Thor made use of the magical axe Jarnbjorn. Seeing that it's an old weapon in the comics, I imagine we'll have Thor going to an old vault filled with his weapons. Let's just hope it's not on Asgard because we know that the Surtur has destroyed everything there.
Though I'm a bit bummed that Thor's weapon won't be a hammer, I still think the addition of Jarnbjorn to the MCU is fantastic. Even if it wasn't some sort of ancient weapon, I would love for it to be something that Thor actually forges himself—just like Iron Man and his first suit from 2008!
I'm just spit-balling here as well, but maybe Jarnbjorn will end up being a temporary weapon, and Thor will get another Mjolnir closer to the one from the Ultimate comics; the one that's a hybrid of a hammer and an axe.
Avengers: Infinity War comes out May 4, 2018.