Answer:
Three little letters, a paradox to some. The worse that it is, the better it becomes.
I have a neck but no head. I have a body but no arm. I have a bottom but no leg.
Sleeping during the day, I hide away. Watchful through the night, I open at dawn's light. But only for the briefest time, do I shine. And then I hide away. And sleep through the day.
This is needed both for courage and hardcover books.
It is weightless, you can see it. If you put it in a barrel it will make it lighter?
I march before armies a thousand salute me. My fall can bring victory but no one would shoot me. The wind is my lover one-legged am I. Name me and see me at home in the sky.