To improve the object must have: God Magic Crystal
Which you can get from tasks, quests, events, or after killing "Predator".
god magic crystal is added, depending on luck of from 2% to 5%
hp- life, mp- mana, mlvl - magic level cas - club, axe, sword, dist -distance
every item you can attach 15 god magic crystal.
Remember, you can not use it on:
arrow gp's etc items, which do not have defense/attack.