I know that Bungie fixed it so that you can't buy it without completing the quest, but I completed the quest. I infused my taken sword into my Dark-Drinker, and now I can't buy another one. Edit: Just for clarification, I had a Legendary Heavy Engram. There is no sword available for purchase at all, just the cloaks. I completed the quest on my hunter, and I can't buy it on my hunter. Edit: Added picture. Cursor is where the sword should be.