I'm not sure what you mean.
When a player kill a player ennemi, the ennemi is dead and the weapon is near his death a player could take his weapons
A la MTA:VC and VC:MP, basically, with a weapon pickup.
This could theoretically be done by detecting the player's weapons upon death before they get removed. Then just spawn a pickup over their body for each weapon, and when another player picks it up, it's removed and gives them the same amount of ammo the original player had. You could also set a timer on them so they disappear after a short period of time. This is just a theoretical method, though. I'm sure someone else can think of a better one.