With your first controller go offline and load up blackops 3
go to multiplayer and add your second pad then start the game when the timer is counting down go to network settings and go online
once in and you can pick a class join a friend it should take you out the game
once it has it will take you to the main menu when you see the screen spam multiplayer with controller one and it will bring you back into local then quickly with your second pad click create a class and hover over the kn-44
from there quickly join a friend and a error will appear just accept it and it will go to the main menu with a stacked ui.
now that you have stacked the ui you need to go onto multiplayer and add your second pad it should bring up your classes then with the first pad in the background click create a class and go onto tactical or lethal and click on anyone you haven't unlocked then hover over unlock and press b with your second pad then go to secondary and hover over any of the locked ones such as the sword or crowbar the on the first pad click a and in the background you will see all the wepons click which one you want and your done!!