With Blacksmithing 5 and a (cheated) level 17 character, the damage on a crafted two handed sword can be 140-227 or 193-312. On level 18 it can be 148-240 or 204-329. In both cases it was a 60/40 split when I tried it, but with enough variation in the 2 stacks (of 10) at each level that that may have been a coincidence.
