Mercenary

 skills are trained by Jaimon in Levant.

Tier 1: Universal Skills
The universal Mercenary skills can be acquired by anyone, without having to learn the class breakthrough skill.

Tier 2: Breakthrough Skill
Learning this skill will let you learn more advanced Mercenary skills, but keep in mind that you can only specialize in three classes and your choice of specialization is permanent.

Tier 3: Specialization Skills
More advanced skills for those that specialize as a Mercenary. The skills Shield Infusion and Blood Bullet are mutually exclusive - when you choose one, you can never learn the other.