From Lotro-Wiki.com

Lore

Since the beginning of time, fell spirits, not the least of which were the Balrogs of Morgoth, roamed the shadow-realm in service to the Enemy. Through foul sorceries, these spirits may stir the decaying bones of fallen Men, becoming terrible wights. To the race of Men, whose spirits pass beyond the world when they die, these monsters are true abominatons.

It is said that when the Witch-king came to Angmar, he exerted dominion over many fell spirits of Morgoth and sent them from Angmar and Rhudaur to inhabit the Barrow-downs outside of Bree...the last bastion of the Rangers of Cardolan. In the Third Age, only the wights remain to tell of those evil days.

Morgoth, Sauron, the Witch-king of Angmar, the terrible Gaunt-lords... all possess the sorcerous power to infuse the remains of the dead with fell spirits in service to the Enemy. Romour speaks of haunted vales in the realm of Angmar inhabited almost wholly by these spirits and the fell wights they produce...

Rewards

Enmity of the Dead I		Upper-Cut	You gain a short-distance ranged attack.
Enmity of the Dead II		Tactics and Might Bonus	Tactics and Might Bonus
Enmity of the Dead III		Man Sword-damage Bonus	Man Sword-damage Bonus