Now I believe there should be some clarification to how AR works, since most players are not very well aware of it. It's quite obvious if you do some testing, and the knowledge has surely been gathered, but here's the basics:
The AR or Armor Rating you see in your status bar is the weighted average of all armor zones on your character. The AR in your status bar is -not- a number that is always taken into account as is in physical damage towards you.
Now in detail, the player has different armor zones like the head, neck, chest, waist, legs, arms and so on. A piece of armor can cover one or more of these different armor zones, and one zone can be covered by several pieces. When a hit lands on a player, an armor zone that was hit is picked and the AR of that specific zone is calculated against the hit. The actual AR of the zone is all natural armor (including blesses) of the player, plus the highest armored piece covering that area. Depending on different factors, a part of that AR is subtracted from the hit's damage.
When calculating the AR of a specific zone, one should note that different pieces of armor have different AR ratings, even if made from the same metal. For example the plate helm protects the head zone much better than a chainmail coif, when both are made from empyrean.
Now you might wonder why a chainmail coif often gives more AR than a platemail helm, even if it protects the head less. The answer is, that a chainmail coif covers two zones whilst a plate helm covers only one zone, causing the AR of the coif to be calculated twice where the plate helm is only calculated once in the average that is shown in your paperdoll.
If you find this completely TL;DR, here's some important points you should pick out:
- When reporting AR related issues, you should list your equipped armor, not your AR rating
Even if you have very high AR, wearing nothing over a specific zone will cause unprotected hits to land
When comparing the AR of items, you should note wether they cover the same amount of zones
