Answer:
It holds most knowledge that has ever been said. But is not the brain, is not the head. To feathers and their masters, it's both bane and boonΒ One empty, and one full.
What is the heart of many risks, has a heart, but is not a living being?
A dragons tooth in a mortals hand, I kill, I maim, I divide the land.
When set loose I fly away. Never so cursed as when I go astray.
What I am filled, I can point the way. When I am empty. Nothing moves me. I have two skins. One without and one within.
Said to have fifty shades
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?