Who is Peredur Long-Knife from Here Lies Arthur and what is their importance?

Peredur is a boy, later a young man, who follows Arthur for a time. Peredur is named after his father, the warrior lord Peredur Long-Knife. After his father and brothers are killed in combat, his mother becomes somewhat overprotective and Peredur, nearly from birth, is raised as a girl. His mother repeatedly cautions him against allowing anyone to see him naked. It is thus only when Peredur begins to enter puberty that many appear to question his identity as a young woman. Myrddin spots the deception quickly but appears to be the only one to see through the presentation.