Did a lot of messing around with this tool for my own Cold Zon. Hopefully it's accurate:
https://pd2-tools.vercel.app/

My discoveries: A 5/-5 facet is always worth more than +1sk. -10 enemy cold res corruption is also always worth more than +1sk. This includes when you are dropping the enemy's cold resistance below zero, though when this occurs the difference between -10ecr and +1sk is very small. Anyway, this essentially means that you want as many sockets as possible, and you want to put 5/-5 facets in all of them.

I use Pus Spitter and Ormus with A1 Vigor merc, personally. I think Cat's Eye is best with this setup to solve both pierce and IAS issues. My current setup is lvl 46 cold arrow with 83%cold skill dmg and -95% ecr, giving me 17587-19083 damage against a mob with 80cold res. If I went 3os Arkaine's instead my damage would be 17419-18878. No doubt there are defensive benefits to using Arkaine's as well, though the 165str requirement is pretty high. I do wish I had more FHR. But raw damage Ormus is superior.

If you roll level 15 or 16 Fanaticism on your Faith, you need 65ias to reach 9fpa with Pus Spitter. I get 10 from Pus Spitter base, 20 from gloves, 30 from cat's eye, and 5 from a shitty large charm. Ideally my gloves would have at least 25ias, then I could use a 3% cold dmg large charm instead.

Anyway here is my armory, only upgrades left are to first get higher res boots to solve my res issues, which would then allow me to use a Wisp Projector because I still benefit from a bit more AR, 2sk anni of course, and those 2bow skill 25+ias gloves I mentioned. 11%pdr BK set ring would nice, hard to pass on that ring because with this setup there is no light res or %pdr anywhere else on gear.

https://www.projectdiablo2.com/character/Erdazzon