The two most obvious concerns are the tires on the tow vehicle and the type of WD system and hitch you are using. Not just the KIND/Brand of anti sway and hitch but how it's adjusted. Your Armada MAY find it squirmy if you have E rated tires on it but that will likely go away after they're worn down a little bit. 10 ply rated tires usually have deeper tread than passenger car tires which are OEM on the vehicle and this alone can make them somewhat squirmy.
Spring bars on the WD system must be correctly sized for the trailer being towed. The normal method is to use 15% of the trailers GVWR as the tongue weight and size your spring bars accordingly. should be as close to this weight but not UNDER it. AFter getting sized correctly they now need to be set up according to instructions from Nissan. Some manufacturers are still recommending that ALL of the front end lift be compensated for with the WD system and others specify that only half of the front end lift be corrected. Get information about YOUR vehicle from it's manufacturer. If they HAVE no instructions I'd recommend you adjust half of the rise out and drive the rig. If it still wanders adjust the other half and try it again.
One OTHER item that you should consider and that is how the ARmada is loaded when towing. How much weight is being added to the vehicle in the form of passengers, cargo or optional equipment? All of those weights will reduce the maximum trailer weight pound for pound so if you are CLOSE and travel well loaded you MAY be overloading the vehicle. I'd recommend you stop at a CAT scale and get your ACTUAL weights so weigh with everything and everyone IN the vehicle and with the trailer loaded as for travel. It's not LIKELY to be the source of your problems since max trailer weight effects only your warranty until you exceed the GVWR or GAWR of the vehicle. If you are over THOSE numbers (located on your door post on the DOT safety plate) then you have a SAFETY issue with the combination but unless you're loading very heavy this is not that likely.
Good luck / Skip