I completed all 4 forges with three black armory weapons equipped (spiteful fang bow, tatara gaze sniper, and the hammerhead machine gun) while also wearing the full black armory armor set. Just did the Gofannon forge (which is the last one I had to do), didn't get the emblem OR the obsidian accelerator, and when I try to go to Ada (which is what the quest step says to do, so I know I've definitely completed all 4 forges correctly) nothing happens. Spent all that time working to get the emblem and special obsidian radiance all for it to be bugged.