Sacrificer is a Legendary Ceremonial Knife for the Witch Doctor in Diablo III, obtained via purchase of Reaper of Souls Collector's Edition (or Digital Deluxe edition) as part of the Arma Mortis pack. It can only be used for Transmogrification.
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Sacrificer
Legendary Ceremonial Knife
"The more subjects from whom I extract souls, the easier the process becomes." — Author Unknown, Armis Mortem