Arthur Weasley never told his family, but the fight between him and Lucius Malfoy at Flourish and Blotts during the summer of 1992 wasn’t their first. They’d once gotten into a physical altercation at the Ministry of Magic over the Muggle Protection Act. He’d been patched up by Perkins, who had been rather understanding and amused about the whole affair, and had even bought him lunch. Arthur thought Perkins was secretly happy that he’d won the fight.
To this day, most people believe that Lucius Malfoy has a scar next to his left eyebrow because he fell down a flight of stairs. He would rather they think that he was clumsy than know that he lost a fight to a Weasley, and Arthur would rather his family not find out about the whole situation.