After recounting everything to Astron, Carl looked at him, checking his response. This fellow before him was regarded as quite highly in his mind and in their circle.
He was especially known to be logical and observant. This was what he had heard from Irina, and in their spar, he was able to conclude this was the case.
With the tools given to them, the tunnel was being illuminated now. The reason why he attacked Astron initially was because he wasn't able to sense him before Astron entered the lethal range.
Astron didn't make any sounds, and his presence was concealed. He wasn't using the light in the darkness either, so Carl then made the assumption that he was an enemy. But then, after he had missed the first attack, he noticed that the enemy didn't have a clear killing intent different from the monster they had encountered.
This made him stop his consecutive attacks, and it was the right choice.
