Heart of the Damned is a heart that can be combined with either the Gram the Sword of Grief or the Short Sword of Mask +4 by Cespenar to make it stronger.
The heart can be found in Odamaron's Lair inside Sendai's Enclave.
|“|| The Heart of the Damned is an ancient dried human heart. It takes its name from the legend of the man that it came from. Legend has it that during a war, the cause of which has long been forgotten, a keep was beseiged. The Lord of the keep knew that his walls would soon be overrun and, rather than have his people enslaved, he slew them all. When the besiegers next attacked, they found the Lord standing amongst the slain.
The Lord was burned at the stake and the legends say that his heart would not burn. The Heart is an artifact of significant malevolent power and may be of some use.