Towards the end of Avengers: Endgame, we see
Thanos fighting Captain America. He repeatedly hits Cap's shield with a big double sword thing, which breaks the shield.
How did this happen? As far as I know, we've never seen anything that can damage
vibranium before in the MCU. Black Panther's vibranium suit is not obviously damaged when hit (admittedly just once, remotely) with Thanos’s sword in the battle. Is the sword made from a hitherto unknown metal?