Another good thing, read the tooltips carefully. For example. Take Warriors lvl 2 skill (the defenseskill, blue-ish icon with axe, dunno how it's called in english ^^)

It raises your defence by 20%, meaning, it's kinda your phisical armour. This results in
-0% magic reduction
- about 7% effective physic reduction. So, it's not like an "inner beast" which will give you 20% off of everything including unicorn-glitter...
Thats also... a tricky but interesting part. Which cooldown is pulled when?

But, don't worry, you'll learn it in time if you are interested and keep reading the tooltip-stuff.