On another post i kind did a suggestion on the craft system:
It dont need to be based on elements,could be ASP or Dex stats or strong against a monster type (wich already have in some weapons and the ones that have a certain stats cant be added more of the same), and about the effects it would be something to think about, i dont know how much resource this would be, but i think it would be nice to have your own custom made gear.
I think your idea is too similar to the Gem system which already exists. You can already craft some gear and depending on which gem you add to your crafted item, it will gain a different bonus effect.
I understand that your idea isn’t exactly like the gem system. However, if in your idea adding an ‘elemental essence’ will also reduce the potential of the item by 1, then IMC simply needs to add more gems that add the effects you described (ASP, DEX, more damage vs monster types) and make it so that you can only have 1 of those type of gems in a weapon at once. Then their Gem system will be pretty much the same as your crafting idea.
For this reason, I do not really see it as being practical for IMC to implement.