Hey there. Did the quest definitely get completed? If you earned the bonus Oversoul 'jackpot' drop, then that would complete step 2 of Bottomless Pit, but since it happens after Crota's death, it will not complete the subsequent 'Kill Crota' third and final step. Additionally, if you definitely completed the quest, note that the weapon does not drop from it directly. You claim it from Crota's sword, which is acting as a vendor, next to the raid's final loot chest. If you missed it that time, you can pick it up on any subsequent completion. The catalyst does not come from the quest or the boss kill, it comes from two timed plate puzzles in the raid, that require Necrochasm to start, and only drops the catalyst for Necrochasm owners. What you mentioned is the triumph for finishing the 'to equip' requirement - similar to how other catalysts require 'X kills' to equip. Necrochasm's 'to equip' requirement, uniquely, can be progressed and completed without actually owning the catalyst or even the weapon. So the triumph showing as complete does not imply ownership of either.