5-8% toughness on Chained Hit.
Up to 5-20% Strength based on the charge time of your heavy attacks. Stacks 3 times.
2-5 bullets loaded from Reserve on Critical Hit.
Shovel because I like the attack pattern. Other viable options are anything that has good armor pen and decent horde clear.
Gorgonum because you can tap fire it to hit long range specialists if no one else is able.
Combat ability regen is personal preference on curios and is the only requirement, the rest are flex picks which I've picked out some good choices. Regular priority would probably be revive speed > combat ability regen > everything else. No toughness regen because you don't need it. Just take a nice medium charge heavy swing and you'll get all of it back in a horde, maybe about 40% if not in a horde.
Alternative weapon setups
Perks