Varika:
I see you already have the Jewel of Darkness. That means you are qualified to become a Dark Wizard. Take the jewel and go to a Grand Master of the Dark Elf Guild in Gludio.
The closest is the village of Gludin. Follow the road and continue on south. Go to the Dark Elf Guild there and meet Grand Master Xenos. He will change your profession to Dark Wizard.