Swiss army knife, one of the mid-sized one like a Tinker. Or a classic folder like a Case Stockman. Nothing too expensive because odds are they break, destroy or lose one or two. It is to be expected so don't freak out when they do. Have them buy the second out of their allowance or in return for chores. It's a knife, and expendable, no matter how special a symbol you want it to be to them, it isn't the Holy Grail.

Show them how to work with it, supervise a couple of times, and show them how to sharpen their knife on a simple carborundum stone with spit. Boys love the spit part. Also how to wash out the inevitable cuts with soap and water and apply a bandaid. Again, don't freak out. Cutting yourself is a normal part of learning to uses a knife.

Cuts will heal faster with a sharp blade and are less likely if the kid isn't trying to force a dull blade to work.

Simple, inexpensive pocket knife, supervise the first couple of uses, teach sharpening with a stone, and how to deal with cuts.