Damien didn't wait to jump back into combat.
He took the Twin Moons out for larger blasts, and even without them Vector Controller was originally a ranged class.
His ability to manipulate vectors was best put to use supporting the girls. He messed with the vectors of the Ghost King's attacks and empowered theirs, making the battle completely advantageous for them.
The only ones not doing any work were Bertram, who was useless in this situation, and Virgil's group, who could only watch in awe.
"Say, Diana, could you ever show this much power at 2nd class?" Marcus asked incredulously.
"Don't even joke about it. They're bonafide 3rd class practitioners with that kind of firepower," Diana responded wryly.
"Who the hell are they?"
Virgil asked the question everyone in their group was wondering about as the battle continued.
Even they were able to understand the Ghost King's mechanics over time.