You can choose Lunging Strike OR Flay, dealer's choice. If you go with Flay, pick Combat Flay (increased Damage Reduction).
If you don't have Overkill unique, use Edgemaster Aspect on 2h Bludgeoning weapon & Rapid Aspect on Ring #2.
Since this is a Walking Arsenal build, you'll be selecting which skill will be using specific weapon choices. If you're on PC, this is done by pressing "Middle Mouse" when hovering over a skill. For Deathblow & Upheavel, you're selecting a weapon that has the highest BASE damage, not DPS - meaning you want to look at the damage on the screen that's an interval (XXXX - XXXX), not the damage per second. What's key here is that EACH one of these abilities needs to have a different weapon assigned so that you can keep up your Walking Arsenal Build.
Weapon Skill Assignments
Basic skill = Dual Wield
Death blow = Highest BASE Damage weapon
Upheavel = 2nd Highest BASE Damage weapon
Leveling
This build is meant for both leveling and endgame. The biggest thing is making sure your weapons are swapped out every 5 or so levels for the best possible one, don't mind the aspects, just get raw DPS while you're leveling.
Gear Progression
I wanted this build to be unique agnostic, but Overkill is a very fun unique to use, especially after Season 2. The goal here is to have Overkill supercharge the hell out of your Death Blow with ranks, AoE damage, and additional charges via cooldown reset.