The gun itself is quite powerful, and its blast radius satisfying. the loss of the arm is painful when you could just otherwise use a conventional gun. though it runs on bionic energy, so that part is nice.
a secondary fire mode where it fires megaman-esque pellets would balance it out; probably even make it op. but attaching a high cost to the pea shooter and/or making it as useful as a lowgrade laser pistol would help. as would the long-awaited bionic overhaul.
its overall a nice attempt to expeiment, and if it offered meta-effects such as improving the armor of the arm its on and such itd be great. or getting a claw attachment for it. or being able to nob off a tentacle or tail to use it. all of which are, currently, nearly possible to edit in.