Blood of the Wrathful

Blood of the Wrathful was required to properly temper the metal of the aptly-named Blood-Tempered Ranseurs. Though the blood of most demons holds a substantial amount of power, common blood was not sufficient for the quenching.

Source
This item dropped from Zelemar the Wrathful in Ragefire Chasm.

As a quest objective

 * The Path of the Adept