Answer:
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair.
I cut through evil like a double edged sword and chaos flees at my approach. Balance I single-handedly upraise through battles fought with heart and mind instead of with my gaze.
I turn everything around, but I cannot move. When you see me, you see you! What am I?
Flat as a leaf round as a ring. I have two eyes but can't see a thing.
I lose my head in the morning and regain back it at night.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?