Is it really 10%

Need advice for Glacian arcane ability. Stated Increase 12 str, 12 dex, 15 int, 10% armor.. If my armor is 10k, 10% from 10k should be 1k. I've checked with 2 calc. But when I click the skill. My armor only increase 500 to 10500. I don't understand. Why?

seems like it doesnt stack with PASSIVE armor (highest buff works)

How to differentiate our passive and active armor? Is it exactly total amount of armour divided by 2.

hello good ty for info