Did you overestimate the dark fog? Wish you could ramp up the difficulty? With this mod you can modify the dark fogs' settings for an existing save.
Currently if you upgrade / downgrade the settings for the dark fog, it does NOT update the metadata multiplier (not sure how to tweak that). Also, I am not sure if this disables achievements.
I don't know how to create Unity UIs (never used unity and not familiar enough with C#), though the way the mod works right now you would still have to save and reload to see the changes because I also don't know how to edit the current game instance combat settings live.