Silver Knight of Marielle before she became Empress.
You met him on your first visit to The Castle. He, along with Taurus created Galahad. The three had a plan to rescue Marielle from the Imperial Dungeons of Arcadis, which the party promptly told them was a bad plan, and forged them a new one.
Antonio has a mechanical arm and leg, and has implied that they were lost during the war.
“Gah, this smell makes me wish they had blown off my face.” -Antonio Losata while traversing the sewers of Bythitor, capital of Arcadis.