Soul Stealer in Heroes 4

Increases the hero's Melee Attack and Melee Defense by 4. For every 2 hit points of damage done, the hero gains 1 hit point.

This weapon was forged from an unholy metal that actually absorbs the blood it spills during combat. Although it transfers some of this stolen strength to the one who wields it, this process is painful. Most cannot carry a Soul Stealer for long.