This was the title given to Xander Vos upon his Knighthood. It is similar in wording to the title that Luke Skywalker gave to Jaina Solo - Sword of the Jedi - although no similarities have been proven.
This title indicates that Xander is the weapon of the Jedi, using the light to defeat the Sith, and return the Galaxy to its balance.
This title also has a double meaning - those who use swords risk harming themselves in the process - which added fear to the Council, who were already wary of Xander after many performances of the Dark Side on his part.
After Xander's death, the title, Blade of Light, died with him. No one known has been given the title after him.