A carpenter I worked with once told me, joking I hope, that he wouldn't know how good his new hammer was until he pounded his thumb with it.
Whatever it takes for the boys to 'bond' with their tools I guess.
Finding out what happens when things go out of control can eliminate the mystery and unfounded fear.
A friend wouldn't drive when it was wet. A problem in a location where much of the year it rains nearly every day. She feared losing control in a skid. I took her out onto a huge parking lot during a heavy rain and had her skid my car on purpose. Inside thirty minutes she was doing four-wheel drifts and 'bootlegger' turns. Once she had seen that, in and of itself, a skid wasn't the end of the world and that they could be anticipated, avoided and managed, even enjoyed, she was far more willing to drive when it was wet.
IMO she was also a much better driver.
Cutting yourself with a knife lets you know that you can endure and survive simple mistakes and allows a lot less fear and hesitation during use. I don't think you need to try every knife, a scalpel feels a lot like a box-cutter with a new blade, but if that is what it takes to know that if you slip a bit your unlikely to die then that is what it takes.