Answer:
The weapon of choice to create the biggest shock.
I'm white, I'm round, but not always around. Sometimes you see me, sometimes you don't.
They can float and tickle, but their sound is rarely heard unless you're a pillow or bird. What are they?
Someone walked into a room and you heard a crash! Someone died. What happened?
Double my number, I'm less than a score. Half of my number is less than four. Add one to my double when bakers are near. Days of the week are still greater, I fear.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.