An Arbiter of Rule is an individual selected by the leader of a faction to decide who would be the next ruler of that said faction after his/her death whenever there is more then one heir to the rule. The Arbiter title changed depending on which faction his/her was deciding for.

In 1170PD, Steward of Katastar Sendil Eilliwood became Arbiter of Rule to the Kingdom of Stars following the death of Andrew Katanova. Were he choose Larissa Katanova as the next ruler.