wěi is archaic. In modern Chinese it survives almost exclusively inside one fixed phrase:
冒天下之大不韪 (literally 'to brave the great not-right of all under heaven') — to dare do what the whole world condemns. The phrase comes from the Zuo Zhuan:
犯五不韪 'commits the five wrongs'. Outside this idiom and historical texts,
韪 is essentially never used.