Answer:
I make you weak at the worst of all times. I keep you safe, I keep you fine. I make your hands sweat. And your heart grow cold. I visit the weak, but seldom the bold.
I wear a red robe, with staff in hand, and a stone in my throat.
You can hold it without using your hands or arms. What is it?
A dragons tooth in a mortals hand, I kill, I maim, I divide the land.
Metal or bone I may be, many teeth I have and always bared. Yet my bite harms no one. And ladies delight in my touch.
I am owned by Old McDonald.