The aide class is your support team members. They are usually the healer of the group.
Aides such as Joan of Arc or Agamemnon wear plate, the rest wear cloth armor.
Aides wield wand and crystal usually, there are a few exceptions (staffs and shields).
Intelligence is an important stat for aides, it increases the amount they can heal your team. Tech does not increase healing effect, only defense against enemies ultimate attacks.