So a lot of people have been complaining that they can't figure out what armor goes on what class, well let me tell you, there's a way to know!
Let's start by pressing 'K' and opening our Class window and going to the Class Roster tab as displayed at the top:
If you note the sections circled in red; the icon is the armor icon that appears on every class and hovering your mouse over it will produce a small description which will tell what armor type that class uses: Cloth, Light or Heavy.
So now you know what kind of armor a character uses, but how do you tell what kind of armor the drop you got is? Well sometimes it's obvious; items called robes are robes and therefore mage equipment and thus cloth, and chestplates are heavy armor but there is an another way!
This is a two step process so please bear with me!
First off, you can actually equip three sets of armor AT ONCE! One for each category of Cloth, Light and Heavy and when you switch class your character will swap to the appropriate armor set equipped on its own. How then do view these sets? Well first you press 'C' to open your character window and look for the circled bit:
Now I'm playing a Hunter which uses Light Armor so the light armor tab is displayed, but you can switch between the tabs to see your other sets so let's do that and look at my Heavy Armor.
Now see the circled area here, same place where Light Armor was displayed except now we're looking at Heavy Armor: Notice how it's greyed out? That's because Hunters cannot use Heavy Armor.
The same applies for Cloth Armor!
Now let's say an enemy drops an item and we can't figure out what weight category its in (Cloth, Light or Heavy), but we know that it is body armor: well handily we have basic body armor equipped in each item set now, because we went and bought the cheapest possible of each kind from the npcs and when we hover our mouse over that item in our inventory it will compare it with the body armor of the corresponding set. Let's look below to see this in action!
See how the game compares those two robes? Well that's because the robe we have equipped and the robe we picked up are both CLOTH armors and the game does this comparison even though I'm currently classed as a Hunter which is a LIGHT armor class. This will work in both the inventory AND in shops, so you can compare your potential purchase with the armor you have in that weight class easily.
Please note you can only equip Cloth Armor while using a class that uses Cloth Armor, and you can only equip Light Armor while using a class that uses Light Armor, and the same applies for Heavy Armor. On the plus side, as each piece of armor, when equipped, is removed from your inventory and stored on your character page ('C' button) that means you're not wasting 12 inventory spaces on armor for each category.
Hopefully this is a little help, if a bit tedious, I'll be working on this guide as I continue to explore the Closed Beta between writing essays for University.