Build goal is to have as much Range as possible so that Grasp of [Lohk] doesn't just become a melee weapon, as well as a minimum of 200% Strength so that [Gaze] will remove all armor from enemies.
Problem with Xaku is that overall his general survivability is horrendous. Even with 75% damage reduction, an AOE attack from a high-level bombard will definitely kill you. Quick Thinking gives you that one chance you need to survive a bit since evasion means none of the stacking defensive mods/arcanes will work. I've tested other mods like [Redirection] (oneshotted anyway) and [Fast Deflection] (might work if you abuse Shield gating mechanics), but generally [Quick Thinking] feels best since with the low Efficiency you'd want to run [Primed Flow] anyway.
Grasp of [Lohk] covers an aspect of that anyway since it disarms opponents while using their weapons against them. The damage is very good since it scales automatically against enemies so unless you're fighting Corrupted/Grineer you don't actually need [Gaze] (from The Lost).
Void damage is, as always, horrible outside of specific niche cases since DE has decided that infinitely scaling armor is a thing, so [Gaze] is very much mandatory if you want to kill things that matter.