Awakened Heroes are ascended Allies. They are deified and their strength is on par with Deities.
To deify them one needs the Hero ally of the desired Awakened.
They are deified just as usual - read the Deify System article for detailed information on that.
They use their own essences - the Hero Essence -, which can be purchased for 30 Rubies each at the Shop or farmed in the last two areas of Chapter 3, Icy Land and Shadow Castle.