Subclass Skill Certification:
Once you reach a certain level of skill in your subclass, your skills can be certified. As a result, you will be able to learn some special skills which you can use in your main class.
However, each subclass slot can have only one certification. That means that even if you come back with a different occupation for the subclass, you cannot obtain another certification unless you first spend a huge amount to cancel the first certification.
If you want to obtain a certification, your current occupation should be that of the subclass you want to be certified, and you should be above level 65. Now, do you wish to be certified for this subclass?
Listen to a detailed explanation about subclass certification.
Get certified.