Quinn comes from the Irish surname O Cuinn, often traced to a root meaning "wisdom" or "counsel" -- originally a family name long before it became a given name. As a unisex choice today, it tends to carry a sense of directness: someone whose judgment is trusted without much ceremony around it.
The lord of the second house hath the same strength in hurting, as the lord of the eighth; the lord of the sixth, the same with the lord of the twelfth. - William Lilly (1602.-1681.)