This is a grapefruit knife. It's made of thin, flexible steel and if you tried to stab someone, it would just bend. You could, if you're a Jihadist, use it to slowly saw a kufir's head off, but it would take about a day. It is, in short, about as dangerous an object as a teddy bear. Yet under 18s are banned from purchasing one, and if you're caught in public with one in your pocket you face at least 12 weeks in prison.
A Judge has decided that it falls within the dictionary definition of a 'knife' as "a cutting instrument, consisting of a blade with a sharpened longitudinal edge fixed in a handle". This is the law at its asinine worst. No excuse.