- Normal: "A one-eyed aerial fiend. It can inflict darkness in the blink of an eye and drive you absolutely batty."
Oversoul: "In addition to its usual gaze attacks, this oversouled fiend has gained the unfortunate ability to attack with elemental magic."
Arhiman have the ability to inflict Darkness, so defeat them quickly by using either normal attacks or magic.
In the Fiend Tale endings, a notable Ahriman fretting over his eye prior to him and Shinra learning of an old man in the Macalania Woods who claims to talk to fiends. However, the old man is revealed to be a schemer as Ahriman's eye is cured by a Gel.