Here are all skill modifiers
https://www.grimtools.com/db/items/skill-modifiers
And here are my two posts with screenshots of some visual changes introduced in specific patches:
Grim Dawn Version 1.1.7.0
Grim Dawn Version 1.1.6.1 Hotfix 1
And here are Visual Changes videos (most if not all of them)
Visual changes of skills through items
If we had much more weird modifiers the game would definitely be harder to balance.