Great chapter.
Read chapter 79 of the prequel and chapter 1 of this series for the answers.
Short version: Edia subconsciously activated Omnipotence after hearing Kawaki's frustrations. It's her Shinjustu ability she awakened after Amado gave her Shinbai's cells. She can't actively use her...
Let's go baby, a one-hit knockdown!
Of course, if she can survive a pummeling from a heavyweight MMA champ, then one punch from Akita won't cut it. Still, I like how crafty Akita is during this fight.