Here is the issue. The exotic swords all have a quest that lead to the final boss fight of Alak Hul. I have just attempted to complete the final part of it 3 times (Separate occasions) and while other that accompanied me were completing the quests for either the solar or void swords, I was attempting to get the arc sword. The fireteams were competent and we completed the quest requirements as described (kill the boss and the assigned warden within 30 seconds). The solar and void sword quests were completed, however the arc sword quest was not. I first thought that we had not completed the objective within 30 seconds. So on two other attempts, the fireteams were only attempting to complete the quest for the arc sword. This is where I realized that it was not the lack of completion on our part but an issue with the game. The quest objective would continue to state that we had killed the warden, but not the boss, even though it was very clear that we had killed the two within the 30 second time limit. Having this fixed would be very nice.