Lee D beat me to it - a Wharncliffe.
A 13yr old boy asks for a Karambit, (I believe) he views it as a weapon not a tool. Personally, I wouldn't fight that, I'd get him a weapon BUT I would get him a weapon with at least SOME more utilitarian application.
I am into FMA, I carry a knife for SD and I don't even carry a karambit. I have one but they are just SO task specific. A Wharncliffe, on the other hand, gives you (almost) the same "dig" as a karambit but is also good for utilitarian tasks and makes for a better thruster. Look at a Yojimbo.
That said - Yes, Fox Knives or Ontario Knives EOD Karambit (fixed blade). Have both except my Fox is the Tanto blade.
I would not try to change him as far as opposing the idea of a SD knife. I would, however, try to find him some FMA training and maybe even buy a couple trainers so you can drill with him.
