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.
You can read it both ways, I wearΝΎ One way it's a number, reversed a snare.
I wear a red robe, with staff in hand, and a stone in my throat.
An iron horse with a flaxen tail. The faster the horse runs, the shorter his tail becomes.
When it comes in, From sea to shore, Twenty paces you'll see, No less, no more.
Walk on the living, they don't even mumble. Walk on the dead, they mutter and grumble.