In Finite Space Visual Novel Official Accountさんのイラストまとめ

Commander Fen Orion is the leader of the Cavalry Knights for the sector and certainly will take no objections, whining or pleads. He will make you all excellent Squires by the time he's done with you.

As part of the Cavalry, Calbex and the other Knights are responsible for engaging the Plague first, be it planetside, or in space. Squires are required to assist their Knights get into their armour at a moments notice, and Calbex is waiting.