Note: this isn't necessarily the sword Excalibur which King Arthur used. It might be. But there's nothing saying that it inarguably is.

Excalibur: at first glance, a fairly ordinary sword in good condition. However, when wielded by someone Virtuous it's magic awakens. Researching its history will invariably produce contradicting results. There are also rumors of dark rituals that dedicate the sword to Titanic powers, changing the Calling from Leader to Tyrant.
Calling: Leader
Purview: War