7.5-15% Weak Spot Damage. Weakspot Kills also ignore Enemy Hit Mass.
3.5-5% Strength for 3.5s on Hit. Stacks 5 times.
Killing an enemy by firing both barrels makes your next Reload 40-70% faster.
7-10% Reload Speed for 3 seconds after Close Kill. Stacks 5 times.
Fire both barrels at close range to quickly kill mutants and elites and get fast reload from Both Barrels & Speedload). Dance of Death massively reduces spread for medium range kills (just slide dodge a sniper/gunner then double barrel them with the tight spread).
Knives for distance.
Rashad with Fury for ogryns/monsters (they bleed on hit giving Scourge crit chance for follow ups).
(Emperor's Bullet for attack speed boost after firing both barrels is nice, but other nodes more important.)
(IJ/Momentum is also great with the axe, but hard to give up ability cooldown with the BP/crit build.)