Joseph was kidnapped by desert nomads when he was very young, and studied the summoning magics offered by their traditions.
He left the deserts at the earliest opportunity and sought to enroll in an arcane university, but though his spells were powerful, the methods he used did not conform to their set standards.
Knowing that the universities would not accept him, he settled for selling his services, eventually joining the Ironsides after proving useful to them in a trial contract.