NAF – New artifacts with unique properties.

Cool, but "Silanna's Shackles," in my opinion, aren't very good. Elves are an attacking faction, and -1 to speed isn't very suitable for them (because it's implied that this is a racial set? Or not?)

It wasn't implied, but it could be, but then you'd have to come up with additional bonuses just for the Ranger (you could come up with an extra set for all factions).

And non-negative luck is only useful against Necropolis, and not always.

Well, not just against Necropolis - Banshee's Cry isn't the only thing that can lower luck; for example, Blood Cyclops and Gates of Chaos, and a bunch of artifacts lower luck, you put on, for example, the Cloak of Deadly Shadows and the Cursed Ring (and so on), attack an enemy, and then there's such a "surprise."