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.
My first keeps time, my second spends time, my whole tells time.
Thousands lay up gold within this house. But no man made it. Spears past counting guard this house, but no man wards it.
What has a spot and is very bright, is sometimes, red, white, blue, yellow or green and is often blinding.
What flies without wings?
What scientists might call your pooch.