I don't think wearing that armor is enough to classify an enemy as "pureblood Garlean" imo. We have at least one case of a non-pureblood Garlean enemy with that model. Sylla mal Albinus of "Scared Sylla" FATE in Azys Lla shares the Centurion model but casts an actual "Cure" spell which discounts him from being pureblood.