Raise the Blacksmith to level 10.

After unlocking the Blacksmith in Act I, talk to him by pressing A and then Y to open his store menu, then tab all the way right to Train. In the Train menu you can purchase upgrades, 5 upgrades per level, that cost an increasing amount as the blacksmith levels up, but also unlocks new items in his weapon/armorcrafting area that you can create. You will need to spend some pretty heavy coin on this, however you will need to be grinding coin anyway for All That Glitters.

The pages and books required to reach the higher Blacksmith levels will drop from Nightmare mode onward, with each harder mode dropping a new item.