Aragorn’s sword in J.R.R. Tolkien’s The Lord of the Rings is Andúril.
Andúril is forged from the shards of Narsil, the sword that cut the One Ring from Sauron’s hand during the end of the Second Age. The reforged blade is made for Aragorn before the company travels the Paths of the Dead in The Return of the King. Its name means “Flame of the West” in Quenya.
Narsil had belonged to Elendil, the founder and first king of Arnor and Gondor. Elendil died fighting Sauron, and the sword broke beneath him. His son Isildur used the broken blade to cut the Ring from Sauron’s hand, making Narsil an important symbol of the royal line.
The sword is sometimes confused with other famous Tolkien weapons. Glamdring belongs to Gandalf, Orcrist is Thorin’s sword, and Sting is the small blade carried by Bilbo and later Frodo.