I've always taken the mysteriousness out of stuff like this. So, he's got absolutely no desire to do anything foolish with it, he's always had a knife and knows how to use it. It's no more taboo to him than a screwdriver, a hammer or any other tool.
This was how I grew up and it worked for me. Everyone is different.
I'm the same way, be it knives, guns, whatever. He'd rather shoot my AR than any .22. That's how I was when I was his age. It's just how it was when we were kids. Hell, remember what most of us did on rainy Saturday and Sunday afternoons? Watched war movies! Could you imagine such heresy nowadays?

The Censor (my lovely bride) would break the "Edit" button!