After checking out a bunch of knives tonight, we settled on a Buck Nobleman:



http://www.buckknives.com/index.cfm?event=product.detail&productid=3573

It has a frame lock which is really easy to use and the knife seems to be a good quality for the price. While the locking mechanism still requires a digit in the blade path, the effort to close the knife is low enough that I'm not concerned its a real risk as long as he is using the knife safely.

Again, thanks for all the input.
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen