At the end of the green sapling, I'd cut a small space, really a small split, to fit the arrowhead type cutting edge. Then, I'd take green vine and wrap the edge in there and get pine sap and melt it in the fire and slather that around the vine everywhere so it would shrink and get hard so the arrowhead would be solid in there. After it was cool so it would be hardened, give it to the stupid kid you mentioned to stick it in a feral pig. Then, you would cook it.
Dried and smashed rabbit backstrap works better for binding material (it's sorta like nylon and epoxy), and you don't need the sap, just water and fire, but I did say field expedient.
There's more than one way to skin a cat. As I said, it's more about attitude and skillsets than stuff.
I did notice that you didn't do much but supervise in that scenario. And I still get stuck cooking...
/johnny