Answer:
My first is in blood and also in battle. My second is in acorn, oak, and apple. My third and fourth are both the same. In the center of sorrow and twice in refrain. My fifth starts eternity ending here. My last is the first of last, Oh Dear.
Long and slinky like a trout, never sings till it's guts come out.
Gets rid of bad ones, short and tall. Tightens when used, one size fits all.
White bird, featherless, flying out of paradise. Flying over sea and land. Dying in my hand.
It's anything but amusing when this body part gets hit.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.