Four mysterious artifacts.

As far as I remember, the Ring of the Ghost always lies in the same chest in the Haunted Mansion (it's not a "hunting lodge" - it's a "haunted mansion"), and the Mirror of the Medusas drops from the Queen of Medusas on the lower level of the Red Gnomes' Stronghold - but these are all minor details.

...and the Ring of the Fae, as far as I remember, still drops from one particularly large dragonfly, which, for some reason, they call fairies...
I know, I know, that "haunted" doesn't mean "hunting," and "mansion" isn't a "small house," but that's how it was called in my localization, so I'm used to it...:smile43:
And I was right about the Mirror. These copies are found in Bracada, if you remember.

In short.
Ring of the Ghost - gives a +50% bonus to the Spirit Magic skill.
Ring of the Fae - a +50% bonus to the Air Magic skill.
Amulet of the Clanker - a +large bonus to Alchemy...
(as they say)

But this is not entirely correct. It's not a 50% bonus, but a bonus of +some number of skill points. That is, for example, if you have Spirit Magic - 7 points, then with the ring, when calculating the effectiveness of spells, it will act as 10 points (approximately - I don't remember exactly, plus how many points).

In general, all these abilities can also be found on ordinary magical items...

That's true. The artifacts are not unique.:(