Aetherflow & Faerie Gauge
Official Lodestone Job Guide (Always up-to-date)
Upon learning the action Aetherpact, you'll be able to view the Faerie Gauge, which displays the amount of fae aether.
Fae aether is accumulated when you use Aetherflow to execute certain actions such as Lustrate or Excogitation during battle while a faerie is summoned. Accumulated fae aether can then be used to perform Aetherpact.