Canonically, the Harvester is the signature weapon of Death, the First Horseman, just as the sword Chaoseater is the signature weapon of his brother War, the Fourth Horseman. Because of its uniqueness, it exists only in Death's hands, and War wields an ordinary scythe in a style merely inspired by Death in Darksiders. However, non-canonically, if the player enters the cheat code "The Hollow Lord", they can then buy the Harvester from Vulgrim's demon store.
Regardless, the Harvester is set to be a weapon heavily favoured by Death in the upcoming sequel, Darksiders II.
First of all, it's free from Vulgrim. When you enter the code and go to the shop, you can purchase this amazing weapon for 0 souls. Also, you will harvest more souls than any other weapon in your inventory, it does more damage than the original scythe, and you can perform more combos. The Harvester is very good against hordes of enemies. And to top it all off, attaching certain enhancements will make you harvest even MORE souls with the Harvester. By attaching the Legendary Enhancement Death's Blessing the weapons damage and souls take from objects or creatures is drastically increased, and to top it all of it has a unique ability of converting damage done to enemies to health.