Add Sub class:
Unfortunately, you are not eligible to discuss sub class.
In order to add a sub class, you must meet some necessary qualifications.
First, you should complete the "Seeds of Chaos" quest. For more information about this quest, visit Hierarch Kekropus in Kamael Village.
You should complete the "Fate's Whisper" quest before embarking on the "Seeds of Chaos" quest, however. You can receive this quest from Maestro Reorin, who lives in a hut east of the Town of Oren.
Second, you should have a profession for your second or third transfer, and each level of sub class should be above 75. If your profession is Berserker and you have Soultaker as sub class, for example, each of two must be above 75 in order to add a second sub class.
Third, if you are an Arbalester, Berserker and Soul Breaker, the road to a third sub class will be open. Experience it for yourself!