What causes the shiny, clean line on the otherwise dull wire of Scout's costume?

The shiny, clean line found on Scout's ham costume came from the knife of Bob Ewell. Bob Ewell, Maycomb's most despicable character, carried a grudge against Atticus since Tom Robinson's trial. Bob Ewell threatened to seek revenge on Atticus for exposing the ugly truth that Mayella, Bob's daughter, tempted Tom Robinson, and Bob physically assaulted his daughter after finding out. On Halloween night, Jem and Scout were leaving from the school's auditorium following an organized Maycomb Haloween event, which included a pageant entitled Maycomb County: Ad Astra Per Aspera. Scout played the role of a ham in the pageant which displayed Maycomb's agricultural products. Mrs. Crenshaw made her costume out of bent chicken wire and brown cloth to resemble a ham. Scout's bulky costume hampered her movement but acted as a protective barrier during Ewell's attack. After examining Scout's battered costume following the attack, Sheriff Tate says, "This thing probably saved her life." (Lee 360)