Riven's kinda mediocre, haven't rolled it that much. If you lack a riven replace it with either Sweeping Serration for more slash procs or Primed Chilling Grasp for more raw damage. Galvanized Savvy is optional for PCG too, though it's pretty good for heavier targets.
Edit: and yes, haven't unlocked the arcane slot yet. You can imagine what it'll do with a maxed arcane.