Why is Excalibur so important to King Arthur?

The magic sWord Excalibur could cut through iron as though the iron was paper. That made it a formidable weapon against even armour. The sheath had magic powers too. If one wore it, they could not lose a drop of blood from their wounds. That meant they were never in danger of bleeding to death. Another reason Excalibur was special was the fact that it was made of meteor iron.