Darkhammer

The Darkhammer is the Mini-Boss of the Snowpeak Ruins in Twilight Princess. When you defeat the creature, it drops the Ball and Chain (not in a treasure chest) and following that you proceed to open the chest Yeta thought had the Big Key, but really had Ordon Goat Cheese.

Perhaps this is in reference to A Link to the Past, in which Princess Zelda, imprisoned in a cell in the dungeon of Hyrule Castle, is guarded by a knight wielding a ball and chain. Upon defeating the knight, Link receives the Big Key. It is probably a type of Lizalfos.

Strategy
Darkhammer will continuously guard his body with his massive Ball and Chain. In order to defeat him, you must use one of three strategies. One is to Clawshot a target behind him, as soon as he motions to throw his weapon. He will pause to pull in his weapon, so slash his exposed tail to damage him. The second is a quicker, but much riskier way. A split second after his weapon lands, roll behind him. As before, slash his tail. Quickly roll behind him while he is spinning his ball and chain(dodging quickly of course) and slash his tail like before.

Trivia

 * The Darkhammer resembles the Darknut miniboss within the Temple of Time, not only by its prefix 'Dark-', but also because of its heavy armor suit and large weapon of choice.