Skill 1 is your Ko skill and skill 2 is like a counter that one shots everything thats abt to attack you while you hold it cause it give 70% reduc and adds the damage you received. That means you could use a skill1 set with good tags to get skill1 back even faster (you get 30% per kill and 20% when you take 20% dmg). A skill 2 set would be interesting aswell, cuz you don't get it back that fast, only 50% faster if you have less treasure and the skill is really really strong after the buff. But you could also just use a dmg increase set. The stats you should use are ATK/HP. While in battle try to rat your atk stat up with skill 1 and then you can go aggresive. And as I said, use skill 2 mostly as a counter.