no. Arbiter is a position, or title. It's the highest possible honor given to a Sangheili by the High Prophets. Arbiters are sent on higly dangerous and usually suicidal missions from which they are not expected to return, making them martyrs of the Covenant. At first, the title of Arbiter was considered a great honor and privilage among the Sangheili. But after Arbiter Fal 'Chavamee renounced the Covenant religion, and was branded a heretic by the Prophets, it became a role given to disgraced Sangheili as a way to regain their Honor, even if it resulted in death. There have been about 19 or 20 arbiters, 6 or 7 known arbiters.
The one from Halo Wars was Arbiter Ripa 'Moramee, the 17th arbiter. 'Moramee was given the title of Arbiter after he lead a coup against his clan leadership on Decided Heart (a Sangheili world), and failing. He was killed by Sgt. John Forge, accompanied by Red Team, during the battle of Shield World 0459.
The one from Halo 3 was Thel 'Vadam. His original title was Thel 'Vadamee Supreme Commander, and Kaidon of Vadam Keep. But after the destruction of Alpha Halo (Installation 04), he was branded by the Mark of Shame and was going to be excecuted, but the High Prophets of Truth and Mecy interceded, and made him the new Arbiter. From there, he went to fight the Heretics on the Forerunner Gas Mine, and began to see the true side of the Covenant. After defeating the Brute Cheiftan Tartarus on Delta Halo (Installation 05), and realizing the Prophets had been lying, the Arbiter dropped the "ee" (a suffix denoting military service) in a way to symbolize him leaving the Covenant. The other Sangheili seperatists did so as well. He went on to assist John-117, and the other humans, on Earth as well as the Ark.
