Penance Brand Inquisitor - kind of stuck @ T10+

Howdy. I'm using PoB and poe ninja for the first time. I decided to try and roll my own build on a random character and random skill, and that ended up being Templar brands into pbod and not rolling my own build, but instead trying to build off others. Templar is neat so far.

https://poe.ninja/poe1/profile/WhiteSkyRising-4060/character/SwornToTheLidlessEye

I have about 10 chaos left. I have a heatshiver and another void battery wand available.

I know I need:
* Finish final lab
* I need a chest, but I'm not sure what the strategy is here.
* I need more defenses, I'm still popping at times in stun lock. Petrified blood stops the instant pops, but at half life, it's still a bit live/die randomly
* I need more offenses, packs aren't melting fast enough in delve and T11+.
* I need to get my gems in order, but a little bit overwhelmed which way to move. I just recently dropped lightning mastery and added phys to lightning over critical support

Can any seasoned vets possibly point out a few key elements that would yield the most gains? Thank you.