A suit of barbed armor or a barbed shield is covered with spikes and hooks designed to injure creatures foolish enough to grab at it.
    While you wear barbed armor or wield a barbed shield, a creature takes damage equal to 2 + one-half your level when you escape that creature’s grab on your turn or when that creature escapes your grab. If you wear barbed armor and carry a barbed shield at the same time, the creature takes this damage only once.

Published in Mordenkainen's Magnificent Emporium, page(s) 8.