I was made by the First, (?)
Under the eyes of the eye. (
eye of Sauron?)
Treasured by the children, (
the nine kings of
men who fell to its power?)
I was never to see the sky.(under the shadow of
Mordor, Gollums Cave,
Bilbo's pocket,
Frodo's neck?)
My treasure caused ills, (
Evil spread, bad things follow)
Although not my designer's aim. (
Sauron never intended it to leave his side)
I was the last free of my kind, (others were mastered or lost or corrupted)
Most of them went up in flame.(?)
No chance you put the answer in plain sight?
The One Ring?