Quick Fix heals you up between engagements, which is especially important after taking damage while acquiring your target with the Damnation, and Battle Hardened keeps you focused when the enemy gets close and starts tossing in tactical grenades. Tag them with your Snapshot Grenade and then shoot down the identified targets.
A good strategy in Warzone and Multiplayer is to take out one or two enemies with the Damnation and then switch weapons once your position is known and you need the faster handling speed.