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In Peter Jackson's film adaption of The Fellowship of the Ring, Aragorn is given a long, Elven dagger by Lord Celeborn in Lothlórien. He uses it at the Skirmish at Amon Hen and in all the battles proceeding this.
It is last seen when Aragorn is fighting an armoured Troll at the Battle of the Black Gate, he stabs the Troll in the foot with the dagger when the creature has knocked him down and is stepping on him.