Shackle

The Shackle is a common equipable accessory dropped by Zombies. It gives you +1 defense, allowing you to take less damage from being hit. Multiple shackles can be equiped to stack the effect. They are very useful early on in the game, before you are able to acquire good armor. After you get any sort of armor, the player may not want to use shackles anymore since it takes an accessories slot which may be better used by equipping something else.

Basically these shackles are very handy for beginning players, but for advanced players they are not worth it because other accessories may be of more use. After finding a suitable replacement, it can be sold to an NPC for 3 Silver.

Shackles become obsolete when the player is able to create Obsidian Skulls, as the skulls can also be stacked and grant +2 defense. The Merchant will purchase the Shackle for 1 silver.

The Shackle might be a possible allusion to the video game Elder Scrolls IV: Oblivion. The Character awakes in prison, with shackles on their wrists.