Weapon refining would probably be fine to re-introduce (although I'm assuming they're going to re-vamp it first) - on Ace nobody really bothered because more or less everything broke after a couple of successes anyway and gemming was a lot easier and cheaper.
Gem crafting is something I think they may never re-introduce - at least not in its current form. It inevitably means tonnes of gems and people +3ing normal items easily. I think gems should be left as drops only. The problem then is what to do about mining as it's pointless at the moment.