I loved this novel, but as Savoy (even adopted) I can not endorse the use made of our beautiful knife in this book: the Opinel is designed to cut a hazel wand, sculpt chamois fir the fire, cut the Reblochon or spread the good alpine butter.
Unless the author is confused with the bor (you're rancid, Malik!), But the opinel certainly not a knife in force in the suburbs of Marseille!