I’m going to be “that guy”.
I understand, as a concerned parent, that you came here seeking advice about what is “normal” for your boy regarding knives and this behavior. Understand, this is the internet, and while there is a huge, and I mean HUGE, amount of knowledge in this forum regarding knives, and plenty of other things, it IS a forum about knives, not a forum about child psychology.
Additionally, while I am absolutely certain most everyone here empathizes with you and your situation, as you can tell, you have already received a number of responses which run the gamut of “It’s perfectly fine,” to “It’s super concerning,” which is to be expected.
The opinions here come from countless years and countless varieties of experiences of the many, many types of people who make up this forum. About the only thing anyone can say everyone here has in common for sure is an interest in knives, but none of us know you, your child, or situation well enough to say what is “normal” behavior in your circumstances. Collective knowledge can be very valuable in certain regards, but this kind of matter requires direct attention, by you, with your intimate knowledge of your child and circumstances, because in the end, we’re not the ones living with whatever the outcome is.
At the very least, it could be absolutely nothing, just benign childhood curiosity fueled by a variety of things he’s either seen on TV, video games, comics, whatever. I had a fascination with knives from an early age, did similar stuff, and turned out just fine. That said, it was a very different time, with very different external influences, i.e. no internet, social media, etc. It could also be indicative of something much more significant, with legitimate safety concerns beyond the obvious one of him sleeping on a sharp knife. By that, I mean mental health concerns, or external concerns such as bullying, trauma, other manifesting fears which should be addressed. I personally would hate for it to be something significant, and it doesn’t get addressed because folks here assured you it’ll be fiiiine.
It’s going to require much more involvement than we can provide you here, and my opinion is worth exactly the same as those who might disagree, which is exactly why we can’t gauge your level of concern for you by remote control. It’s not an objective matter. I do truly appreciate that you reached out to a forum you felt would be helpful, and I hope it is, but we’re not there in person to assess a bunch of other factors. To me, if you were concerned enough to reach out, that’s concern enough. I think you should parent the heck out of it until you aren’t concerned anymore, but how far you have to go can only be determined by you in person based on what you know and whatever help you can get at the scene, so to speak.
I hope you sort it out, and that all goes well.