The way the system is set up is as follows (as of about a month or two ago, it wasn't like this at launch):
There are currently 4 levels of armor for each class which dictate how much armor they will have.
The base armor, which you get when unlocking a class is level 6. The can be crafted or found in a chest.
The color variants for the base armor are level 12 and can be crafted or found in a chest once the base armor is unlocked.
The upgraded armors are available once the base armor is crafted and they are level 10. Upgraded Armors in this case refer to either the secondary armor set (in your case the Dread Reaver set) or the Inquisition Captain's set. These can only be crafted.
The upgraded armor color variants are level 15 and can only be crafted.
So, for the sake of ease of communication I will call these as follows:
Base Armor (level 6)
Base Variant (level 12)
Upgrade Armor (level 10)
Upgrade Variant (level 15)
On top of all of this certain classes are in higher loot tables. This means if you're new to MP you're going to have a small pool of classes you could theoretically get from chest unlocks (though you can craft whatever you want).
The tiers for these are as followed:
Tier 1: Keeper, Legionnaire, Archer
Tier 2: Templar, Elementalist, Assassin, Hunter, Reaver
Tier 3: Katari, Necromancer, Alchemist, Arcane Warrior
Dragon Loot (threatening and above): Virtuoso, Duelist, Avvar
Hope that helps 