Excalibur, not to be confused with the sword in the stone. Arthur got this sword from the Lady of the Lake with Merlin's help. It came after the sword he pulled from the stone and was said to be the mightiest sword ever forged.
The sword in the stone. Contrary to common belief, this sword was not Excalibur. King Arthur recieved Excalibur from The Lady of the Lake later on after the sword in the stone had been broken in battle.