Excalibur

One of the four Swords of Power, this sword was held by King Arthur, and later, John Dee.

Dee eventually merged it together with Clarent to create one sword. (He did not know they could merge before he merged them.) When Dee fell into a leygate in the Tower of London that led into an unfinished shadowrealm, he found out about the true power of the swords: making leygates. This sword eventually became part of the Hook of Aether.