Suggestion to make the new leather equipments that will come with the Combat update more balanced with the others types (plate and cloth):
Divide the [Leather Mastery: Dexterity] attribute in two attributes: [Leather Mastery: Physical Dexterity] for Archer and Swordsman class, and [Leather Mastery: Magic Dexterity] for Cleric and Wizard class.
The magic dexterity attribute gives you Magic amplification, and the physical dexterity gives you critical.
Another suggestion is to increase the defense stats of leather equipment so they can have the same impact as the others types of equipment, individually, without needing the set bonus to become attractive/worth. example:
X item-level plate piece of equipment stats: 400 P.Def + 200 M.Def = 600 mix def
X item-level leather piece of equipment stats: 200 P.Def + 200 M.Def -> 300 P.Def + 300 M.Def = 600 mix def