Have you read Lois McMaster Bujold? Or maybe Halo? I'm specifically imagining something like the "needler" in the Miles Vorkosigan adventures. In the books, the weapon is a sleek looking device.

I found this definition: A needlegun, also known as a needler, flechette gun or fletcher, is a firearm that fires small, sometimes fin-stabilized, metal darts or flechettes.