Mr. MakgSnake did not know how to???
*******SPOILER SPOILER SPOILER SPOILER SPOILER*********
Mwa ha ha ha ha, it wasn't either the dart or the sword (if you use the sword you cut him and he says "Damn kid!!! and shoots Raiden) and I did not dare to use it many times so I would not end up killing him or he killing me. So I thought it'd be fun to beat each other's arses with our own hands, and certainly, after some rounds of fists and kicks, I knocked Snake down. While he was knocked down, I shaked him, and indeed, the dog tag jumped out from him
Thanks guys, you are the best
Edit: The dog tag says: Solid Snake