I'm having the same issue, I just completed the Lightfall campaign on Legendary difficulty and never received the exotic weapon option at the end. I did receive the triumph tho, and claimed it but it didn't fix it. I really hope Bungie fixes this issue soon, I just returned to the game after years away and this is the first thing that happens. This sucks but at least other people are experiencing the same problem, so maybe it'll be noticed and worked on. Details: Platform: Xbox Series X Name: Flappylips1