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.
Mars of a nativity, and not joined to good planets, signifieth the native to suffer by envy and hatred. - William Lilly (1602.-1681.)