Eremiel didn't expect that Arthur's attack would chop off his right arm. It was all because of that sneak attack from under his feet that he hadn't seen coming.
Not only was his arm cut off, but his weapon, which was also of the Mythical Rank, had dropped to the ground with it.
Unfortunately for him, Thirteen didn't give him the opportunity to recover his arm or his weapon, swiftly pulling them all into Rocky's Mobile Fortress.
After realizing that his opponent was capable of killing him, Eremiel was forced to make an important choice.
Stay and fight, or flee to live another day.
Although it would take a long period of time, he was confident that his arm could be regrown using the technology that his people possessed.
The weapon he lost could also be replaced, so making the decision was easier for him.
Without even saying a word, Eremiel opened his wings to fly away.