"Well, it's no great hall, but this Sunspear Sanctuary is certainly better than where I was headed before you rescued me. Now that I'm here I can show you how to change your secondary profession, if you're interested."
Zuwarah will change your secondary profession to any available profession in the game (provided you own the relevant campaign). If you have never had that secondary profession on your current character, she will ask for 500 gold; pay her and you will have a new secondary profession.
You can change your secondary profession back to any one you have had previously by going to the Skills and Attributes panel (by pressing "K" on the keyboard) and changing it back using the drop down menu.