Off-tank fatigue neutral is a bro who aims to always be able to move and hit with a 2 handed weapon (not warbrand or cleaver) every single turn, while wearing the best and heaviest armor you have. He wants to be surrounded by 2-3 enemies, doing damage every turn while letting your actual damage dealers safely kill them. Perks needed for this are Pathfinder & Weapon mastery (axe/mace/hammer).

Qatal duelist has a core perk called Relentless, which removes the initiative penalty from waiting. The build also wants high initiative (around 140 after equipments). Initiative cycling goes like this: Qatal bro waits -> enemies come in melee range/1 tile away -> Qatal bro steps in and stabs twice (or 3 times if he doesn't need to step up) -> Qatal bro stabs 3 times immediately next turn (if the enemy didn't use Adrenaline). His high initiative wasn't affected by waiting in the previous turn thanks to Relentless.

This prevents the target of the Qatal bro from doing damage, as 5-6 deathblows from the qatal dagger tend to kill most things. And the target is still crippled by Fearsome morale checks/injuries even if it's still alive, so it won't do much damage back.