Answer:
I bind it and it walks. I loose it and it stops.
At night I come without being fetched. By day I am lost without being stolen.
It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter.
My first master has four legs, my second master has two. My first I serve in life, my second I serve in death. Tough I am, yet soft beside. Against ladies cheeks I often reside.
I climb higher when hot, But beware my rage, I’ll kill with a breath, If I can escape my cage
I go in hard come out soft. Blow me hard and I’ll make a pop.