Must the third item always be a groove cutter? For the Young dragon weapon which currently has possible to combine an item (3/4) the black smith at He Fei accepts weapon, accepts jade seperator and refuses anything in the third slot including groove cutters. A small message flashes across saying not enough resources.
Hi! I didn't try to make the dragon weapons 4 slotted, but maybe you should use a groove cutter (hermit). One of my league mates told me, he couldn't refine the first level of the dragon weapons, because the npc simply refused to work with the weapon. It's possible, that you should turn your weapon into the 2nd level of the dragon tier (jade dragon?) and try adding the 4th slot then. (Also worth to mention, that according to some forum posts, the second level of the tier has the highest refine success rate.)
Hi, I refined it to level 9 currently and you are right True dragon weapons can only be only use hermit grove cutters for the last slot with a jade seperator. Thanks for the tip!