hobbler

noun

1. (historical)One who by tenure was to maintain a horse for military service; a kind of light-horseman in the Middle Ages who was mounted on a hobby.

   “1954, James Francis Lydon, The hobelar: An Irish contribution to medieval warfare, Irish Sword, II, v, pp. 12–16. However superior the Norman knight might be upon the field of battle, the bogs and woods of Ireland gave little opportunity for the mail-clad charge. Thus there evolved in Ireland, as a habitual part of every Anglo-Norman force, a type of light horseman, which came to be known as the hobelar.”

   “no man shall be constrained to find men at arms, hobblers, nor archers, other than those who hold by such service”

2. A small horse.

   “The horse was one of the finest I had seen, not a hobbler. This was a far more delicate creature.”

3. An unlicensed pilot, casual dock labourer, etc.
4. A man who tows a canal boat with a rope.
5. One who hobbles.