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 you proceed to open the chest you  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.

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.

Stragedy
Darkhammer will continue to guard his body with his massive Ball and Chain. In order to beat him you must use one of two stragedys. One is to Clawshot behind him, as soon as he motions to throw his weapon. He will temporarily be pulling in his weapon, so slash his exposed tail to damage him. The second is a quicker, riskier way. A split second after his weapon lands, roll behind him. As before slash his tail like the other stragedy.