You will get this weapon as a part of the Monk’s Missive questline, where you need to challenge and beat Dryleaf Dane. The Smithscript Cirque is another amazing standard weapon that you will ...

The Curseblade's Cirque belongs to the Curseblades. These enemies have a chance to drop it upon dying. The Curseblades aren't hard to find, as they inhabit almost all the Realm of Shadow.