Was his first name given in the novel? We know that the brother's wife had an affair with Ouyang Feng and begat Ouyang Ke. How exactly did the brother and his wife pass away?
Did Jin Yong mention anything about this brother in his interviews? Such as how talented he was?
I'm just speculating, but I imagine the brother must have been more powerful than Qiu QianRen's twin brother. Qiu's twin must have the same reaction speed and nervous system quality as QianRen, so the twins were equally talented but I think only QianRen was taught the Iron Palm, since he was the one who saved clan leader Shangguan.
Since the White Camel Sect's rules state that there can only be one disciple, so is it possible that the elder brother knew NO advanced martial arts at all? So regardless of how talented he was, he could not become very powerful without strong arts for him to study.