So, I was thinking recently, and I have no idea if someone has suggested this before or not, but here I go;
What I propose is that you be able to "apprentice" under the smiths of the various factions. What do I mean by this? Similar to how you currently have Buy/Smith/Exchange Coins, you could add an "apprentice" button.
If you have under 1000 alignment with the respective faction, the smith will say something along the lines of "I do not give my trade secrets away to just anyone, come back when you have a little more notoriety [player]"
However, with 1000 or more alignment, the smith will say "So you want to learn the forging secrets of [faction]? Fine, but I'll need you to do something first." And would then give the player a quest. It could either be simply one of the quests which the faction already gives (For example, a dwarf smith could ask you to kill 30 gundabad npcs), or it could perhaps be a new custom quest to give them a weapon or tool with specific modifications, the specifics don't really matter. But once you've completed the quest, clicking the "apprentice" button again will now open a new screen, similar to the trade screen, except the smith is now selling you smith scrolls of some of the better versions of modifications (Ex; Enduring Scroll, Legendary Scroll), to represent him teaching you some of the smithing things he knows, but for a price of course (lessons don't come free).
The reason for this suggestion is to help alleviate some of the grindier aspects of the late game, in this case, repeatedly reforging or grinding NPCs in order to get weapons, tools, and armor with the specific modifiers you want, and due to the alignment, quest, and cost, I feel it's a reasonable barrier to get a nice selection of modifiers.