What is the ruling on fighting and brawling with someone who insulted one's mother and sister and almost hit them? Is it permissible to hit him and use sticks and iron to prevent him from repeating his actions? What is the meaning of "whoever points an iron object at his brother, the angels curse him"? Are there any hadiths that prohibit striking a Muslim in the face?

You are permitted to repel someone who intends to strike your mother and sister with whatever deters him. If you are killed in the process, you are a martyr. Similarly, you are permitted to curse him with the same words he used to curse your mother. However, as for pointing an iron object at your brother, the angels will curse you until you abandon it, even if he is your full brother. Striking the face in combat is forbidden.