[Valerius]

I like your list, except for the flying ship, with which I've had some bad experiences.

So, here's a first draft. We can also fill out the list with non-unique, rarely forged, items.

Level 2:
The Sharpest Tooth
Sandals of the Crane
Holger the Head
Percival the Pocket Knight
Alchemist's Stone

Level 4:
O'al Kan's Sceptre
Winter Bringer
Rod of Death
The Flailing Hands
Fenris's Pelt
Krupp's Bracers
Carcator the Pocket Lich
Tome of the Lower Planes

Level 6:
Aseftik's Armor
Monolith Armor
Robe of Calius the Druid
Flesh Ward
Pebble Skin Suit
Boots of Calius the Druid
Tome of High Power
The Black Book of Secrets
The Tome of Gaia
Ardmon's Soul Trap