Rime-Coat Raiment's icicles most often times interfere with whatever weapon you're using, causing on-kill perks like demolitionist to not activate. In the footage provided, I was using a Judgment of Kelgorath with Enhanced Demolitionist and Enhanced Wellspring. You can see that after the first kill, i was granted roughly 30% grenade energy back. After placing a turret and gaining Bleak Domain though, one kill granted the normal 30% grenade energy, and the other granted none. I haven't tested this with other weapons yet, but am more than willing to do so if it would help to fix this bug. It seems to be happening very consistently with Kelgorath. I also have a solar siphon equipped in this footage, which are suffering from the same problem, and you can see that it doesn't activate after the multikill.