EDIT: found this on the wiki: Upgrade components
All armor pieces come with a special slot where an upgrade component can be applied. These components grant additional bonuses to the armor, granting an advantage to characters in combat. Each upgrade component has six levels of bonuses. For example, for each Crest of the Legion a scholar has equipped, he gains one extra bonus from the Crest of the Legion bonus list. If the crest is added to each of the six armor pieces, all of the bonuses that the upgrade provides will be unlocked.