If you are a Gunslinger, I've found it is easier to use Knife Juggler with Sealed Ahamkara Grasps (or Gamblers Dagger) than getting the grenade kills. If you get a throwing knife headshot kill, you get 35 points for a melee kill AND 45 points for a precision kill which totals the same amount for a grenade kill. You also get your throwing knife back and if you miss, you have the extra one there. See the video for a nice Throwing Knife kill spree.