The Collaborative International Dictionary of English v.0.48:

Heelpiece \Heel"piece`\, n.
   1. A piece of armor to protect the heels. --Chesterfield.
      [1913 Webster]

   2. A piece of leather fixed on the heel of a shoe.
      [1913 Webster]

   3. The end. "The heelpiece of his book." --Lloyd.
      [1913 Webster]