Deathreach is a Legendary Fist Weapon for the Monk 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.
Legendary Fist Weapon
"It occurs to me that human souls might be alloyed with more than base metal. Their essence could likely be contained within energy matrices as well... or perhaps even within the light and harmony that makes up angelic forms. If those energies could be controlled, they would prove a source of immense power." — Author Unknown, Armis Mortem