Carrick, congratulations on realizing that there are no pigeon holes in this game! You can make any kind of patch-work character you want with mixed armor, weapons, and spells, and have a blast! I'm not too familiar with DK so I can't offer much advice there, but I can offer advice on the crafting.
There are two different types of named armor sets in the game: a) Those you loot in the world (cannot be crafted) and b) Those you unlock by researching traits on armor/weapon pieces (can be crafted).
For (a) you are limited to what you find while questing and what can be purchased from others in a guild store. For (b) you have to invest skill points and time into researching traits (ie. Divines, Impenetrable, Sharpened, Well-Fitted, Exploration, Weighted, Infused etc.) for each piece of armor that you'll be using. Trait research takes days. The more traits you research on a piece of armor or a weapon, the longer it will take for the next trait until you have all 9 traits researched. Tamriel Foundry has a great article which shows you the crafted named sets, how many traits need to be researched per piece to unlock that set, and where you can find the special set crafting tables (since the set must be crafted at its own specific crafting location).
Hope this helps! If you spot me in game, I'd be more than happy to help with any questions. I have a slew of traits already researched for light/medium armor and woodworking so if you're wanting to get into crafting sets I can provide pieces for you to research anytime.