Im not sure if i understand the question, but if ya speak of Special Abilities (SAs) a weapon can have (starting with c-grade) for Duals, u need to enchant em to +4 to get em. Normal Weapon can have 3 different SAs on them and u use a Soul Crystal of a specific stage for it. Duals just have 1 possible SA and it comes along when the Duals r enchanted to +4 or more. Remeber that its only save to enchant to +3. With +4 or higher there is a 50:50 chance that u crush ur Duals :)