In the Avengers: Endgame we have seen how the mad Titan, Thanos nearly destroyed Captain America’s shield which is made out of vibranium. If something that damages the caps’ shield then it has to be stronger metal than Vibranium. In MCU, Cap’s shield is not unbreakable….. Evidently. which makes perfect sense considering that the shield is only made of vibranium and not with adamantium like it is in comics. Moreover, Vibranium is a key part of what makes Adamantium indestructible but it by itself is not.
There are a couple of theories which suggest how the Thanos’ blade is made of… Let’s see what they have to tell.
Theory 1: Is the blade made from Uru?
In the Marvel Universe, few metals are stronger than vibranium (besides Adamantium which supposedly doesn’t exist in the MCU). One such metal is said to be Uru – an enchanted on cosmic metal from the home of dwarves and their forge in Nidavellir. Theoretically, Uru is known to be stronger than vibranium and Marvel Universe ranks it as a top-tier metal that doesn’t manage to come out on top of Vibranium in some aspects. This might be due to similar properties but Uru is enchanted with magic.
Theory 2: Is it made from Yaka?
One of my other guesses is that the sword could have been made from Yaka, a metal that Yandu’s arrow was made out of. one of the special features of this is that it just get through anything it went up against at 70 miles an hour like it was nothing. Purchase of a shield as its weak spot especially Swords due to their general design. However, Yaka isn’t much stronger than vibranium but it can break it with the strike like the one given to caps shield in Avengers: Endgame.
Theory 3: The Blade could have been made from exotic materials like the Chitauri armor & weapons
In the Avengers: Infinity war, we saw Thanos pushing his fingers into Visions skull (made of vibranium) with ease. To get the mind stone out, he crushed visions skull with his bare hands. we know that Thanks is one incredibly strong dude and if he was given a massive version of miniature blade that he gives to his daughter Gamora to play with, and allow him to use the blade to smash repeatedly downward upon Caps’ shield which is at an odd angles to catch the blows on the very edge of the shield and we certainly have a problem.
Presumably, the Mad Titan had his blade made from exotic materials like the Chitauri armor & weapons, which is also extremely hard and Powerful. if the blade is driven downwards with all the Thanos incredible strength that is focused on the edge of the display and transferred on to the edge of Caps’ shield. Moreover, Thanos is a veteran and the master of combat or even better than Steve Rogers. Above all that he knows how to swing that oversized blade. so that might be the reason he didn’t strike the shield anywhere near the center but attacked near the edge, so it was more like a cutting action not breaking action.