In the opening sequence, we see Gorr having to bury his daughter as they're lost in a barren wasteland. After she passes, Gorr finds an oasis with his god there, enjoying the fruits of his labor (or lack thereof). Among the god is a mysterious figure with the Necrosword in its grasp. We never learn what this creature's name is.
Many may be quick to assume this is Knull, an eldritch god of darkness and the creator of the symbiotes in Marvel Comics. He's a pretty important figure, though, and it would be strange to off him in such an unceremonious manner. Ultimately, we don't know who this being is, but it could have some serious ramifications for the future of Marvel films.
The Necrosword and Knull are intrinsically tied to symbiotes in the comics, and of course, this introduces the idea of the likes of Venom and Carnage making their way into the MCU proper. We already know that part of the Venom symbiote is in the MCU thanks to the post-credits scene from "Spider-Man: No Way Home," so it's possible more symbiotes could make their way into this universe with the Necrosword out there.
Of course, the film ends with the Necrosword being destroyed, but where there's a will for symbiotes to factor into the MCU, there's a way.
