Anyone who swore an oath in front of Excalibur would indirectly acknowledge Levi as their master.
Of course, to succeed, this kind of oath had to be sworn by the person who took the oath and recited the corresponding oath, supplemented by a specific Sword Acceptance Ritual. Therefore, it had to be an intelligent race that could speak.
In addition, just like many contracts, the person swearing the oath could not be much stronger than the sword master. Otherwise, the oath might lose its effectiveness and backfire on the sword master.
"After the Truth Magic Mirror, Teatime Round Table, and Excalibur, only the Holy Grail of Immortality is left... The Holy Grail of Immortality, Diuxis, was refined by the Immortal Banyan Dragon. I wonder what it does...
