1. Chillrend
Description - A glass shortsword colored blue instead of green that causes frost damage upon strike.
How to gain - Complete the quest 'Killing Field' set by Valus Odiil in the Grey Mare Inn in Chorrol. Complete the quest without either of his sons dying.
2. Umbra
Description - A jet black long sword capable of trapping souls.
How to gain - Either complete the quest set by Clavicus Vile or simply travel to the Ancient elven ruin (CBA writing the name, can't spell it :/ What is it, ayelid...?) west of the imperial city. Enter the cave and find Umbra (Regardless to player level, she will always wear Ebony armour, so lower levels, take advantage!) Note, she will put up a hard fight, and is extremly difficult to kill if you are unprepared. Good luck!
3. Debaser
Description - A short sword carried by Hortinor (Incorrect spelling...? Okay, the guy who gives Thoriner his stock) that is a dull grey and covered in symbols. I do believe (but I am not sure) that it damages attributes. It's not worth much, but it is a one-of-a-kind!
How to gain - Complete the quest 'unfriendly competition' and collect it from the Hortinor. DO NOT kill him during the quest, the quest will remain uncompleted FOR EVER.
4. Blackwater Blade
Description - An enchanted steel short sword. damages strength and/or agility.
How to get - Spend a night aboard the ship/inn at the waterfront. You will wake up and a quest will start. Complete the quest and get the sword from the captain.
5. Amelion Cuirass (Not the actual name, there's another word in the title of the item, but it still comtains both words.
Description - A silver Cuirass (Light armour) with frost resistance and carvings covering it.
How to get - Go to the cave named 'Amelion tomb' (follow the eastern bay up from Leyawin.) Go inside, hunt around a little bit and the chest piece will be there. You can also complete the fighters guild quest where you must retrieve it to pay off a debt. However, you can pay 1000 gold and keep the cuirass. NOTE - it is not a quest item and can be sold/dropped.
I will add more as I progress further into the game. Apologies for the holes in the information but I promise, I will plug these ASAP. Also, add your own knowledge of special weapons and armour here for all to see! Any questions or help needed, my xbox Gamertag is crazyfoomandude.
Good hunting, guys, and good luck!