Whole sets of armor may be crafted to unlock classes and to get higher tiers of each armor set. The way that it works is: if you don't have a class at all, the first time you craft their armor, you unlock that class. That then lets you craft variants of that outfit with higher armor values. It also unlocks a separate, higher tier of armor for that class, which has a different name. Once you craft that outfit, it unlocks variants of that higher tier, which have the highest of the crafted armor values. You can tell by the name: the variants have the same base names, just with added adjectives/nouns.
Let me use the Silent Sister as an example. Let's say you don't have her, you want to unlock the class. You would therefore go and craft the "Silent Sister's Cuirass." This unlocks the character, and you can play it. Now if you were to go back into the Armor Crafting menus, you'd see that you could craft four new armors for the Silent Sister: The "Silent Sister's Cuirass of Blood," the "Silent Sister's Cuirass of Bone," the "Silent Sister's Cuirass of Sinew," and the "Silent Sister's Proving Cuirass."
The various "Cuirass of [stuff]" armor are just color variants of your base outfit with higher armor values. Notice how the "Silent Sister's Proving Cuirass" has a different base name and costs slightly more materials to craft than the others. This is because it's considered a higher tier of armor. If you were to craft this and equip it, you would see that it actually changes the character's base model. Once you've crafted the "Proving Cuirass," it also unlocks the "Silent Sister's Proving Cuirass of [stuff]" armors to be crafted. Those cost even more crafting mats and are the same color variants, this time of the "Proving Cuirass" model. Most importantly, this last tier has the highest armor values that you can craft.