Manacle Barbs

Source Advanced Race Guide

Barbs added to these manacles wound a captive who does more than move slowly and with care. A creature secured in barbed manacles takes 1 point of piercing damage if it takes more than a single move action during a round. Rough movement of any kind, such as being struck in combat or falling prone, likewise causes 1 point of damage. Attempting to break out of barbed manacles with a Strength check deals 1d4 points of piercing damage to the captive regardless of the success of the attempt.

Fetters can also be fitted with barbs, but the wearer can avoid damage by not taking actions that involve moving its legs. hobgoblins often use such fetters to secure artisans to their worktables. Securing a captive with multiple sets of manacles and/or fetters doesn’t cause additional damage.