Umbral Enhancement III is bugged and not working as expected for the season pass weapons rank up weapons, Cold Denial and Falling Guillotine. The recaster perk description states: "Weapons obtained from Focused Umbral Engrams drop with an additional alternate final perk." This perk works for all of the new arrival weapons except for Cold Denial and Falling Guillotine. I tested this with Rifle, Edge, Arrival, and Pyramid-focused Umbral engrams. Whether they came from Arrival-focused engrams or Pyramid-focused, Cold Denial and Guillotine both rolled with a single final perk every time.