From my gist of VD's initial post, advising him to engage in an physical conflict with his brother probably isn't the best thing.
It seems as if his brother is potentially searching for reasons to erupt; if he's retaliating at simple, harmless verbal remarks, challenging him could have unwanted consequences . . . incidental serious or fatal injury.
VD should probably confer with his parents before he decided to act or try something like that; if both brothers still live at home, an altercation could unfavorably complicate or escalate matters to an even worse extent. [His parents do not need additional stress or woe.]
If VD's brother isn't open to communication, I seriously doubt a physical beating would influence him. In his mind, it might even justify some opinion or secretive reasoning that he already harbors.
Just my take on it though.