Gefeios said your skills had improved and you would need a suitable weapon. So you obtained Vorpal Essence, a Shulack Refiner and a Blessed Aurium Ingot. You managed to refine these in the Jotun Studio and create a crystal. The crystal is Siel's Essence. You brought Siel's Essence to Gefeios, who used it to upgrade Siel's Gleaming Sovereign Aether Key.