Another idea is to make weapon upgrading modular. You can basically upgrade say with lighting and fire stones but depending how many stones you use will determine the damage output. In other words the physical damage could be 15%, fire 15% and lighting 70%. There would be a limit to how many times you can upgrade and probably be the same amount of times you upgrade the normal path.
Blacksmith will sell embers (or you can kill them for them) so you can smith your swords at bonfires and prevents you from smithing paths (only the certain paths you don't have embers for) on weapons if you don't have them.
EDIT
(Just edited the percentage values as I put 30% in both instead of 15% and changed 60% to 70%.)
Last edited by steveswede on Tue Apr 23, 2013 11:02 am; edited 2 times in total