Cake can occur at any moment and quite unexpectedly so it make sense a prepared person would have a knife at all times.
Kniv s are good and chefs are good with knives...Your nephew...maybe not so much, although I'm sure he got better. How many fingers does he have now?
Fortunately, he didn't lose any fingers. It doesn't take long to learn to give a good knife the respect that it is due Ha !.... but I tried to warn him to keep him from needing to learn it by surprise from experience. Some folks just need THAT experience though I'm guessing.
Cutting oneself with sharp knives by accident is a good lesson in not doing so being preferable.