Arbiter (Earth-2042)

"The Taming of the Lekgolo, the Unggoy Rebellion. Were it not for the Arbiters, the Covenant would have broken long ago!"

- High Prophet of Mercy

Arbiter is a title of the highest possible honor bestowed upon a Sangheili. Formerly appointed only by the Hierarchs of the Covenant during a time of need, the title is currently held by Thel 'Vadam who leads the Swords of Sanghelios after the Covenant and the Galactic Empire's dissolution.

The title was originally the greatest religious, military, and political rank of the Sangheili. After they joined the Covenant, however, the role was downplayed in importance somewhat, with the Sangheili High Councilors ranking higher in political matters. This would eventually change again: approximately 400 years before the Clone Wars, an Arbiter declared he did not believe in the Great Journey and was stripped of his rank and killed. Thus the title became a brand of shame. Arbiters were sent on highly perilous and suicidal missions by the Hierarchs. On these missions, the Arbiter was expected to die and to become another great martyr of the Covenant on their path to the Great Journey. This was seen as a way to regain, in part, their honor. Depending on the nature of his assignment an Arbiter would have either acted alone as a singular combatant, with support by Covenant military forces, or they were tasked to lead large numbers of Covenant troops.

Source

 * https://www.halopedia.org/Arbiter