Great idea just came to mind! Though this just turned into a bigger project
Skill Dual Wielding would use specific 'Off Hand' weapons. The Off hand weapon should level just like the main hand as they strike.
Off hand weapons will naturally deal less damage, exactly how much will need sufficient testing. This is to balance the overall damage boost when gems are also included.
We would need weapons of each of the three types ie Slashing, Stabbing, and Blunt for each 10th level, we could recycle some graphics or.. hold this project until we can add more graphics.
Off hand weapons are generally smaller, so as not to get in the way of the other weapon. Unless we don't care bout all that
Edit: I am aware this may not be currently possible, all I ask is a lil acknowledgement that it's a potential goal for the future
MORE details :
It should be noted for the sake of balance I think if it's possible for a penalty to parry (the action not the skill), at worst a 10% penalty to parry at 0 skill when wielding an off-hand weapon. This penalty reduces to nothing at skill 100 and the Off-hand weapons should give no defensive bonus, (maybe even a small defensive penalty, I can't propose how as I don't know exactly all the numbers >.>)