Armor weight modified proficiency = base proficiency * (1 - 0.01 * effective armor weight)
Effective armor weight = 2*head armor weight + body armor weight + leg armor weight + 6*hand armor weight - 10
There are three possible factors reducing your wpf. First reduce your wpf by 13 for each point of power throw, then reduce your wpf by 14 for each point of power draw and then remove 1% of remaining wpf for each point of effective weight.
The same mathematically:
(wpf - 13*pt - 14*pd) * (1 - effective weight / 100)
That's what it used to be. Don't give a fuck about the Power Draw thing, I'm pretty sure it is different right now.
But if u're not playing thrower or archer:
For example, u are a Kuyak-Hero.
Heavy Kuyak: 14,1 kg x 1 = 14,1 kg
Nordic Warlord Helmet: 2,7 kg x 2 = 5,4 kg
Heavy Gauntlets: 2 kg x 6 = 12 kg
Rus Splinted Greaves: 2,6 kg x 1 = 2,6 kg
= 34,1 kg - 10
= 34,1 kg --> 24,1 % less wpf. Or if u want it that way: 75,9 % of ur wpf is effective.
Now IF:
It is not 100% like that, but basicly, ur IF reduces the effective armor weight by 2 kg. So basicly, for every IF point the pentalty gets reduced by 2%.
Let's say you're 24 18, have 7 IF, your wpf pentalty is at 89,9 % instead of 75,9 %
Some things I just said may be wrong, as they have been changed (maybe). From my own experience: If u wear anything over 15 kg IF is a MUST, if you don't want to hit like a turtle.
And don't take heavy Gauntlets.