As a soothsayer he practiced extispicy, the observance of animal entrails to foresee future events.
He is also referred to as Arexion the Arcadian (Ἀρηξίων Ἀρκάς) which indicates he was a native of Arcadia, a region in the center of the Peloponnese.
[3] Arexion the Seer is mentioned twice in the Anabasis, the first time being when the army is in Port Calpe in Asiatic Thrace.
After Arexion's sacrifice did not give good omens, the Greek army waited a day.
Later Arexion is mentioned sacrificing before the battle with Spithridates and Rhathines from Pharnabazus, this time obtaining favorable omens with his first sacrifice.