You know, you might try a two pronged approach. Do the fixed blade thing as you have stated, on a trip/when you're around. AND a small pocket knife for him to carry AS YOU TELL HIM HOW TO KEEP IT IN HIS POCKET, THAT IT IS NOT A TOY! If he handles that responsibly then you have your answer as to if he is ready for his own. I BOUGHT my first knife at around 9 or 10 years old. I was in the 3rd grade so I guess I actually would have been 9. Only told once to "put it in your pocket or it's mine until after school"!

Just my 2 cents, nothing more.