According to the legend of King Arthur as depicted in Sir Thomas Malory's "Le Morte d'Arthur," Arthur did not originally acquire Excalibur; rather, he obtained a different sword from the Lady of the Lake.
In the story, the young Arthur, before becoming king, is sent by Merlin to retrieve a sword from a lake. Arthur comes across the Lady of the Lake, who is an enchantress, and she presents him with the magical sword Excalibur, which he uses to prove his rightful claim to the throne by pulling it from a stone.
The sword in the stone is a crucial part of Arthur's destiny, symbolizing his rightful kingship and his divine approval. After he pulls the sword from the stone, he is acknowledged as the true king of England, and Excalibur becomes his legendary weapon, associated with power, chivalry, and destiny throughout his reign.