Answer:
I am a busy worker who is a water mammal.
I belong to you but others use me more often than you do. What am I?
I sleep by day, I fly by night. I have no feathers to aid my flight. What am I?
I cannot be other than what I am, until the man who made me dies. Power and glory will fall to me, only when he last closes his eyes.
Blade to blade I always win My foe laid low and even. Yard by yard through thick and thin I'm busiest in season.
I have feet on my head