fana was more about the damage it gives to the demon, im not sure if its worth to trade it for holy freeze while i understand that holy freeze make proc curse whhay faster and yes i watched you video the tainted demon is enought to kill ubers/colossus and they werent even with barb bo/shout.
need to run some tests maybe the ideal build would be with 1 point blood oath since whatever the fire damage of blood boil kill the max tainted would kill as well in that "range"
i was running freeze on my demon for a while but I recently swapped the fanta and I think I prefer the latter. The demon attack speed is noticeable for tougher heralds with immunes/extra strong/stone skin etc. As for all the others, they die so before the amp is even applied. I think fanta affects the tainted too.
The demon only has 5% chance to apply amp with its attacks. Holy freeze on a pack of 20 monsters has a 64% chance to proc amp every 2 seconds. Once it does proc amp, its getting 2-3x the damage.
Fanat will only add 127% ed and at best something like 23 -> 22 fpa normal attacks, not entirely sure about jab speed. And 100% AR at least.
The demon already has up to ~1200% ED here, so you're maybe raising overall damage per attack by ~10% with fanat. And it has a 15 frame delay between each attack and already has 60% EIAS of the max 75% EIAS. Spearwomen have 18 base frame animation for 2HT normal attack, so breakpoints at 0/6/13/20/29/39/50/64% EIAS for 17/16/15/14/13/12/11/10 frames in their animation, +15 delay so that makes it 26->25 FPA.
Amp is by far the most important thing here and you absolutely 100% crucially need to spread it reliably.
The only reasons to skip holy freeze on demon is if you're either exclusively killing ubers, where it does nothing, or you're applying amp by some other means ie dreadfang merc. And you're using an infinity merc here, and sure aren't using gavel swap.
So its not even a comparison, holy freeze + cursed is so important that a basic TZ cursed mob upgraded to aura enchanted already has all the relevant functional affixes you could get besides maybe lightning enchanted, just so the sparks also help spread amp