[Bug] "#% reduced effect of Curses on you" desecrated mod doesn't work

Steps to reproduce:
- get shield with desecrated mod "#% reduced effect of Curses on you"
- get Soul Mantle body armour
- cast a totem skill several times until you get a Vulnerability curse
- the curse shows 3000 (reducing flat amount of Armour)
- equipping the shield or unequipping it doesn't make any change to the number, only passive skills with the similar effect reduce the number