I'm not sure if you are the one who downvoted, but the defense is far from low, I have roughly 70k eHP and as you can see in the videos, I can clear every terms with no difficulty, I even farmed 40k merits with this setup.

Maybe the problem is the way you play and not the build itself.

So, basically you need exactly 1230 Spirit to do a good rotation with her. With 1000 you can use Rage of Xiphos 4 times during each Heven's Fury phase and it takes roughly 8s to fill that up, with 1200 you can use Rage of Xiphos 5 times during each rotation and it takes roughly 10s to fill that up so it's a net gain; I add an extra 30 spirit because sometimes it bugs and you go into Heven's Fury with less than max Fury.

Now that we worked out the kinks, open up with Angelic Smite to knock the boss down > use a medikit to gain 100 spirit > Rage of Xiphos + Know my name and weep, now that you've applied the vulnerability and bleed (it's very unlikely that writhing ribbond didn't proc thanks to row1talent2) you can use your signature for maximum damage, after that Ichor's Wrath + Stunning's Ichor and use any other power as soon as they come off cooldown until you gain max Fury.

When you have max Fury, spam Rage of Xiphos until you run out, then KMNAW > SI > IC > AS and go on again until you have max fury again

I was using WSJ before I got a cCTC, it's not the best item in term of DPS but it gives a good chunk of health. Einherjar Brooch, Edge of Infinity or Vibro-Smashers are also good alternatives.