I'm glad the Demon survived because we actually have an antagonist for a while.
It's actually funny. In the WN, He actually died right here because he was the one who kept yapping about his superiority that when Sasha insulted him as tactic, he lost his composure and suffered numerous lethal injuries rather just a singular slash that made him unable to escape.
In here, Sasha was the one who was yapping about teamwork and acting high and mighty which gave the Demon the opportunity to escape.
If Sasha does not suffer any consequences for this next arc, she will never will.