Glaive is helpful for this, too. You can't aim it up or down, and the lack of a crosshair makes throwing it a bit difficult, but because it's silent you can literally kill targets under the eyes of other targets without being detected, provided you're hidden properly.
Ash's Shurikens are silent and can be used while invisible. I made a build combining Energy Siphon, Smoke Bombs, Shurikens, Streamline, Fleeting Expertise, Continuity, and Constitution. The invisibility lasted long enough that I could waltz into one of the areas and just Shuriken everything to death, and they were so cheap that Energy Siphon provided more than enough energy.