[aron9forever]

in plugin for m4 you create a native player_equip_special_m4 or whatever
in plugin for ak47 you make player_equip_special_ak47
plugins only do what is needed for weapons like setting skin, sounds animations etc, maybe also remove on death or round end

in 3rd plugin, the actual menu, shop, or whatever plugin, you create your menus, all other logic (money price or XP or whatever) and when you need to give the player the weapon you just call the native

all info needed to do this is in the tutorial you were given above; but you can look at how natives work in a real example, just search for any AMXX API (like cs_set_player_team)