The Despair's blueprint cannot be purchased on market, but it is included in the What Stalker? bundle. The blueprint can also be acquired from the Stalker.
Characteristics
This weapon deals primarily Script error: The function "Proc" does not exist. damage.
For effective use of non-hitscan weapons, it is strongly recommended to learn Leading. In short, Leading means aiming ahead of your target so the projectile still hits him. It can be a challenge to learn it, low level Grineer are recommended for practicing.
Notes
Prior to Update 9, there were no knives visible in the quivers. Unknown if intended or not.
The trails from thrown blades are affected by your energy color. (Seems to only work if you are the host.)
Bugs
Currently, while holding a Datamass, there is no proper "animation" or "alignment" of the Despair, for running with the Datamass. The Despair will float above/outside of your Warframe's hands, as if you had a pistol in your hand instead. This problem also occurs when performing a Jump Kick.
Trails from the blades are much brighter with longer decay times since Update 11. This may be an intended effect.
Trivia
A "monofilament" is a fictional type of wire, consisting of a single strand of strongly bound together molecules. This theoretically creates an edge that is micron or even nanometer thin, the sharpest possible.
Typically, they are applied as a cutting tool or a weapon that can sever nearly any object or other molecules.
Organic molecular wires have been proposed for usage in optoelectronics.