Every Unique Item I've found minus the pink Diary which I let go before taking this picture to recollect unbound.

[THANKS OBAMA]

https://imgur.com/a/Mjqj5pD

Only things in it that aren't unique are the two final Merris weapons. I assume they added Angling, more attack projectiles, and pierce recently as a modifier.

[THANKS OBAMA]

The Free Spirit, Spirit Knives, and Witchsword are my absolute favorites. I've kept every unique item I've come across, barring the pink diary, even if I never intend to use them again bound or not.

[PotatoScav]

what happen if you sell them.

[FormidableWolf]

There's also:
Heavy Metal Greaves (Feet, Heavy) which allow you to upgrade a skill to mythic
Signet of Mastery (Ring), +6% master offers
Belt of Bob, 50 armor (Love the inscription of this one)
And whilst not a unique there is a relic which gives you a dragon companion

[-KS-Sylia]

missing the dagger that summons a dragon, necromancer's neck, and dragon scale hp relic

[zordrak]

would be great to get a complete list

i just checked my collection i can add these to the list

amulet:
double rainbow amulet E

rings:
volcanic ring R

jewel:
azure jewel R

relics:
skeleton key M
basilisk scale R
dragon scale R
message in a bottle C
the quest R

belt:
good rope R

armor:
trollstone R
black cape R

helm
ancient helm R
holy cowl E

hands:
command of the five elements E


weapons:
Hack & Slash R Greatsword
Diabolic II M Greatsword (attacks apply burning, +100% burning dmg)
Godrage M Axe
The Wizard of Ooze R Staff


some of the names and additional descriptions are hilarious. Thats something i really like about this game

edit: of course that list already exists... should have checked first xD