Arbites
3.5-5% Strength for 3.5s on Hit. Stacks 5 times.
7.5-15% Weak Spot Damage. Weakspot Kills also ignore Enemy Hit Mass.
6-12% Critical Chance for each Enemy Hit by your previous attack. Stacks 5 times.
Increased Cleave on Critical Hit and gain 10-25% Ranged Attack Stagger.
Makes use of Stance for Double Double Barrel madness. Castigator's Stance is a great panic button for when you need to refill toughness or kill a bunch of elites. You can either do double barrel shots or single barrel, depending on how many buffs you have stacked, how close you are, and what you're fighting.
Dog for far-away specialists.
Any melee weapon is fine. Faster weapons that benefit more from rending are best.
Tac Axes benefit greatly from the rending in this part of the tree and aren't reliant on stagger. Once you get your buffs from shooting stuff they shred, and still perform fine in a horde with no buffs. Light attacks do the job most of the time.
Shock shield offers a breather if under pressure by a lot of ranged enemies and the special is useful if you need to make space before popping Stance.
Single target: Light 1-Heavy-Light-Light
Multi target: Heavy 1-Light