Multiweaponing must be done with weapons of the same series. In your case you are able to combine it with other Foursis weapons( Wired Lance, Assault Rifle, and Rod)
Converse with fellow players
The real issue is that the PC Japanese version of the game added Dualshock 4 support with launch of the Playstation 4 version of the game, which is now "mysteriously" absent from the NA client. My guess is that Microsoft intentionally removed support for it for one reason or another.