To question Helterskelter's crafting skills isnt really fair, imo. When it comes to crafting, there are certain expectations that is set forth in the game. You can be a level 100+3 crafter but fail a level 1 synth. I believe when Mumi's claw busted that was only 1 of a few in which has busted in his experience from what I have heard at that time. It is just unfortunate that the chance of it breaking actually came into play in Darwens synth as well. We must get a bonecrafter that high in the LS so that this can be kept within LS, but i know it is being worked on.
~Pitlith