Swords of Sanghelios

Faction description
"A break-away faction of the Covenant, led by the Sangheili. The Separatists no longer look to the Prophets for leadership, and thus have no defined leadership save for the surviving Councilors, although Arbiter Thel 'Vadam and a few other head Sangheili, such as Rtas 'Vadum, hold positions of power within their ranks."

Gameplay Wise
The faction, also referred to as SOS is one of the two of the hardest factions to join. The ODSTs and the SOS have a rigorous process when regarding applications, and the only playable species at the current moment is Sangheili in the SOS. The player characters in the SOS faction are given extra health in-game to imitate shielding, the HP increasing when they reach a higher rank in the faction.