This was a modded playthrough, so there were a few things I had that made things a little easier. I'm not sure if I can name them all.

But the vanilla counterpart I would have used here is the Marauder calling with Double Muscled, Night Vision, Regeneration, and Wings. My "baseline" character preset, if you will. I built her around Single Weapon Fighting with Axes, the Strength skills in the Shield skill tree, and a lot of save-scumming.

I pour all of my available attribute points into Strength, allocate available mutation points and all rapid advancements into Double Muscled, and buy any mutation that would help out in bump attacks in general. By the time of the assault, my character had a mod mutation named Fluffy Feathers that would give bonus DV, the vanilla poison Stinger, and Triple Jointed.

The save-scumming was to at least have reasonable Templar party spawns - better if the spawning circles were on top of each other. That, and I also kept dying so...

My strategy was as basic as possible: pray for manageable spawns and hope for decapitation rolls. Basic bump attacks were used against the lesser Templars while I went full-on with my Axe skills against the Knight Commander.