Answer for Tutenstein : The quest doesn't matter at all, just ignore it. When you're gonna beat vulcan it will count like you've beated every quest, forexample I didn't finish the forge of themis cause I sold my imp branch, but in the end it wasn't requered to finish the game.
Just figure out the stuff for those weapons you make in the spacial forges by matching up an item to the silhoutte. Those items should be your bread and butter, nothing else is really necessary unless you plan on going all in on the game.
