+52.5-60% Weak Spot Damage (Enemies with Bleed Stacks).
+12-24% Rending on Enemy Weak Spot Hit for 3.5s. Stacks 5 times.
+3.5-5% Critical Chance on Weak Spot Hit until your next Critical Hit. Stacks 5 times.
+1-4 Burn Stack(s) on Critical Hit to a maximum of 3-12 Stack(s).
This is a high(er) skill floor build to capitalize on Vet's damage talents. Push attack spam on knife is your best single target dps and is sustainable thanks to the 2x0.25s stamina regen reduction talents. Serrated Blade lets us take Mercy Killer. Mk6's horde combo is L1H2. Most enemies will die in 1 or 2 pushstab headshots. Crushers and Maulers in 3 - a lot has to go your way to get them down to 2. You'll need a good knife and/or a crit and/or Focus Target active (if you choose this keystone) and/or active talents For the Emperor! and Surprise Attack and Close Quarters Killzone coming from stealth (so once every 45s minus CDR)
With this build, recon lasguns have good dps (even against armor) and good ammo economy (helped by Infernus and Shock Trooper). VId is generally the best choice. Dumdum is an alternative to Headhunter. Deathspitter isn't terrible either.
You should have 2-3 toughness curios to improve survivability helped by Iron Will and Confirmed Kill. You could take Deadshot instead of Precision Strikes if you're a memelord but you'd probably want a slower firerate mark (like VIIa) and a +3 stamina curio.
Poxbursters, or the mutants that bring you to them, will be your number one danger. It won't be crusher/mauler packs or large rooms filled with shooters - you're built for those.
Use Infiltrate to regain your toughness and reposition. Holding block as you go invis is a good habit. Stealth is also great for objectives - pop it before you pick up batteries or start a hack.
Smoke grenades are a bit of a meme, but they're taken to save talents for elsewhere and can be clutch in a pinch. Throw them down on your team when they're in danger against shooters. Dogs also apparently have a hard time finding targets in smoke?
If you really want a keystone, drop the +25 Toughness talent for Focus Target, though understand that it'll be somewhat situational given how many things are taggable in Damnation HISTG and you may not reach new breakpoints on knife.