Liethiel has the soul of Eve and is her very first reincarnation. Thus, her soul is more powerful than those of most angels and living beings in her world. Which is quite important, too, because after a period of questioning her position in Heaven and searching for a fulfilling job, she settled on the newly founded occupation of Head Angel for Divinity Reestablishment (when I think of a better name, I'll edit X'D). In this capacity, she makes sure the new net of divine energy around the world is well-connected with its inhabitants and those that are devout get the benefits of miracles.

She's also the first in her family to really give Arzael a chance. When she was little, she went to him to spite her parents who were very much against the high angel. She never quite understood, why and has befriended him. Which, too, comes in handy with her current occupation.