Answer:
When I get closer my tail grows longer, but when I go away my tail leads the way.
What kind of running means walking?
There are millions of me. I am very small but when moving fast I am deadly.
You must keep this thing. Its loss will affect your brothers. For once yours is lost, it will soon be lost by others.
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.
What covers its face with its hands, speaks no language, yet most known what it's saying?