Unlike Dark Spirits, enemies who appear as Arbiter Spirits are always other players, as opposed to NPCs in-game. Arbiter Spirits invade the worlds of sinners in order to hunt down and kill them for their transgression. Killing a friendly character, or invading and killing another player, will make the player susceptible to invasion by Arbiter Spirits.
Arbiter Spirits also appear in the form of friendly phantoms summoned specifically to help a player kill an invading Dark Spirit. These Arbiters will be unable to interact with the environment, and the only entity they can damage or take damage from is the Dark Spirit who invaded.
Rewards for Killing a SinnerEdit
If an Arbiter kills a sinner, they will be rewarded with a Token of Fidelity, which can be used to duel in the Blue Sentinel Arena in Heide's Tower of Flame. Arbiters receive no souls for killing their targets.
Killing an ArbiterEdit
If an Arbiter Spirit is killed, the player will be awarded souls. The sin counter will not go down, nor will it go up.
Being Killed by an ArbiterEdit
If the player is killed by an Arbiter Spirit, their sin counter will go down by one.
- On PS3 and Xbox 360, Arbiter Spirits can invade other players regardless of the version of the game they're playing, which, in other words, means that a person playing the original version can be invaded by a player playing the Scholar of the First Sin-edition.