Drakman NPC can be found on Map1, at the event. During the event, every monster can drop Spirit Ball. You have to bring 10 pieces of it to Drakman who will get you his chest in exchange. If the event finished, Drakman return to his world and he will not be available.
If you have 5 Silver Medals, you can buy 1 Gold Medal at Blacksmith. If you have 3 Gold Medals, you can buy 1 Diamond Medal at BlackSmith. So: 5 Silver Medal -> 1 Gold Medal, 3 Gold Medal -> 1 Diamon Medal
Plus against Monsters:
Plus against Half-human:
Plus Skill Damage: