The only thing Arthur could do was pretend to reach the seventh circle and go with the others to the battle. He thought about staying below that rank, and then fleeing the school to help his friends, but that would not work.
Sure, he could use the anchor to quickly disappear from the school, but the rank 3 mage would notice he was gone after a few days, and then his disguise would be over.
Still, getting into the seventh circle that fast would shock even the rank 3 mage, but there was nothing else he could do. Arthur was hoping everything would work out, and the rank 3 mage would not kill him on the spot.
Then, he pretended to enter a secluded training for the entire month, increasing his power gradually. He remembered there was a person who kept a close watch on him from time to time.
"What? He is already reaching the sixth circle? This is beyond precedents. Is he trying to reach the seventh circle to fight for his school? What a good lad!"