Weighted Knife is inconsistently refunded when it kills a scorched target (while Radiant and with the Knock 'Em Down aspect equipped, of course). I found that this happens more often when it defeats a target that has been Scorched for a longer duration, but sometimes there seems to be no reason for it not to be refunded, and rarely, the melee refunds when the Scorch or Ignition damage kills the target. Due to the nature of Ignitions, being that whatever first applied Scorch stacks is counted as the Ignition source (despite that you might have triggered it with something else), targets that are killed by the Ignition and not the Knife directly are never counted as melee kills, and therefore do not refund the knife, and are never considered melee kills for exotics, mods, etc. Incidentally, this is likely the very reason for the inconsistency in melee refunds. Aside from this, I think that Ignitions triggered by the Weighted Knife should be sourced from the melee, rather than whatever applied the Scorch. This would make it a little more flexible and more rewarding to build into. Here is a video for demonstration: https://youtu.be/2Yr3QOxt8vc?si=-o4SVVydQWrjBj2W