Aragorn’s sword the Narsil had been famously shattered into pieces before the Lord of the Rings trilogy and was then reforged from the shards into the Anduril by the Elves in the last movie. Man At Arms: Reforged recreates that in real life by building the Narsil and then breaking the sword (it wasn’t tempered after heat treating) only to reforge it into the Anduril.
To make it even harder on themselves, they used a bunch of old methods to make the sword too.
