Regarding the upgraded damage boost from blacksmithing lvl 5 when upgrading a weapon at a whetstone - there isn't one?
One of my characters has lvl 5 blacksmtih, and the other has 2 (for this test). I dropped a lvl 5 blacksmithed 2hand sword with a damage range of 94-158 on the whet stone and the output was 117-189 (level 11).
On my other character, using an identical crafted weapon, with 2 blacksmtihing the damage range is the same at 117-189.
Also, you cannot boost a crafted weapon that received the damage boost random property from lvl 5 blacksmithing, I'm assuming this is on purpose as to my knowledge no other damage boosts stack or are doubly applicable.
However, the 'broken'(?) whetstone boost stinks.