Answer:
My teeth are sharp, my back is straight, to cut things up it is my fate.
What can be heard and caught but never seen?
I cannot be other than what I am, until the man who made me dies. Power and glory will fall to me finally. Only when he last closes his eyes.
I'm tall in the morning and short in the noon. I disappear at night but I will be back soon.
I wear a red robe, with staff in hand, and a stone in my throat.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.