I similarly didn't think there was anything up with his eyes,
until I read the description on Thancred's buffs/debuffs during the duel. Him having a sort of aether sight would explain seeing through illusions and why Thacred slowing/halting the flow of aether in his own body would make him invisible to Ran'jit int he middle of a desert in broad daylight.


One thing that confuses me about his first appearance.
Why let the crystal exarch go? He just helped to spring Minfilia out of Eulmore custody and help the WOL and Friends escape to Il Mehg. I would think the time for diplomacy is passed and he could just capture the CE. Afterall the CE even says he's out of tricks now after stopping Ran'jit from giving chase.