There seems to be a bug where the Quest Log doesn't update when you pick up the piece of Sussur tree bark. 
Because it doesn't update, it acts like I have none in inventory so the forge doesn t work at all.
If anyone can tell me how to get the Log to update so I can complete the weapon, that would be great. 
Weirdly enough, the Quest Diamond follows me around so the Map acknowledges that I've picked up the piece of bark.