I absolutely disagree about the Green Eye. I think it is one of the good
artifacts, and it sure as Hell should not become a non-unique item. In my
current game I have been using a Warlock with a rune-smasher, the Green Eye and
a focus to Hellbind enemy commanders. Nephelle was one of the prizes. Yes, a
ring of sorcery or wizardry bring half the penetration, but the Sleep autocasts
are nice as well, and not everyone has the astral ressources for the rings.
I think the Green Eye is one of the perfectly balanced artifacts.
The best artifacts are Magebane, Aegis, The Barier, the hammers of the Forge
Lord and the Cyclops, The Summit, the Boots of the Planes, and the Gateway.
There are other good artifacts, indeed, but the above are exceptional.
Of course, anyone building a strategy around one of these must remember that
one can wish for artifacts. I fondly remember the game in which I snatched
Magebane from Odin's hands before a major battle.