Chain Knife

The Chain Knife is a new weapon introduced in version 1.2. It can be found from Cave Bats as a rare drop, Skeleton, and from chests. The Chain Knife has a very short range of only twelve blocks. However, its quick use time and velocity makes it a very excellent early to mid game weapon. It is good at killing quick flying monsters. It is also good at killing large groups of wall creepers.

It is similar to flails and the harpoon weapon in the fact that while the weapon is retracting to the player it can deal additional damage to monsters caught in its path.

Trivia
Might be reference to Skorpion from Mortal Kombat and his signature hook attack (rope with a dagger on the end).