Leona is a powerful hand to hand fighter. She also has her strength amped up by Orochi. That said, she will not be able to match Akaza. He is a pure demon so his abilities are not limited by mortal constraints. Leona would barely even be able to track his movements during this fight and that’s what will put her at a disadvantage. Akaza can also heal from any attacks she can throw out which really puts her in an unwinnable situation. Akaza wins.