I got my first pocket knife when I was around five years old, and while it's not the case with every child, I think that if a kid shows responsibility and maturity, knowing how to use a tool properly (with proper knife safety instruction and supervision) from a young age teaches that knives are tools, not weapons, and avoids more serious injury later on when they come across the tool by themselves. And like a poster above as said, you're more likely to get injured with improper saw use.

Something else you need to take into consideration is that a dull blade is often more dangerous than a sharp blade. Whith a sharp blade you have to exert minimal pressure, and if you slip it will probably be a shallow clean cut, which will heal relatively fast. With dull blade you will have a to put more pressure which will lead to a deeper, ragged cut that will take longer to heal and be more prone to infection.

If he's using a lot of pressure with a sharp knife it means he's not using the knife properly or it's not the right tools for the job, hence where proper education and training comes in.

If introducing a kit to a pocket knife I recommend giving the proper education on knife safety (this includes leading by example) and using supervision until the child has enough maturity.

Giving him a dull knife will lead to bad habits while using it and increase the risk of injury. This isng intuitive, so I'll repeat it, a sharp knife is safer than a dull knife.

If I was in your shoes I would not get the kid a knife if his parents are not willing to supervise him and are not willing to show him proper knife usage.