My boss has both the pistol, and the carbine. I would not call them failed. They work, but the project was extremely rushed, so quality and reliability took a major dump.
For a gun in Destiny, like everyone said, it is literally what the Cabal use. So a Human version of the Cabal gun would be pretty cool.
It is funny however since we already have this in the game: Skyburners Oath. Having a more refined version, without the insane bullet drop, and lack of RPM would be neat.
I work at a gun shop that's been around since the 70's. We see a LOT of cool stuff, and the boss has some good taste. The pistol is like holding a narrow brick, lol. Cool aspect is that the hammer for the gun actually struck the Microjet from the nose to to have the firing pin strike the rear of the projectile. One of two reasons that I can come up with was that since the Microjet did not generate enough thrust to get out of the barrel with much of any velocity(you can stop it with your finger), the projectile being delayed by the force of the hammer having to be -blam!- back by the Microjet would provide enough resistance to get the projectile to generate enough thrust, and not to mention the gun has no recoil, so they had to come up with a different way for the hammer to be -blam!- back by the guns firing sequence like in any other semi-auto.