The Eye & Hand of Vecna - Lotsa good lore

 I'm not a sucker for lore, but this one has got me interested. 

https://dumpstatadventures.com/blog/deep-dive-history-of-vecna

via

https://dumpstatadventures.com/a-players-perspective/a-players-guide-to-artifacts-ii

Quick summary from them:

Eye and Hand of Vecna

Wondrous Item, Artifact

Seldom is the name of Vecna spoken except in a hushed voice. Vecna was, in his time, one of the mightiest of all wizards. Through dark magic and conquest, he forged a terrible empire. For all his power, Vecna couldn't escape his own mortality. He began to fear death and take steps to prevent his end from ever coming about.

Orcus, the demon prince of undeath, taught Vecna a ritual that would allow him to live on as a lich. Beyond death, he became the greatest of all liches. Even though his body gradually withered and decayed, Vecna continued to expand his evil dominion. So formidable and hideous was his temper that his subjects feared to speak his name. He was the Whispered One, the Master of the Spider Throne, the Undying King, and the Lord of the Rotted Tower.

Some say that Vecna's lieutenant Kas coveted the Spider Throne for himself, or that the sword his lord made for him seduced him into rebellion. Whatever the reason, Kas brought the Undying King's rule to an end in a terrible battle that left Vecna's tower a heap of ash. Of Vecna, all that remained were one hand and one eye, grisly artifacts that still seek to work the Whispered One's will in the world.

 

 Check this out:

The eye looks like a bloodshot organ torn free from the socket. To attune to the eye, you must gouge out your eye and pop in Vecna's. Simple, right? The eye will attach itself to the eye socket, appearing as a golden cat's eye. The eye stays in place until you die, which will happen immediately if you remove it from your head. 

Properties of the Eye. It's not surprising your alignment changes to neutral evil. 

Other crazy stuff, some negatives unless you find and attach BOTH the Hand and the Eye. If you only have the eye, for instance, 5% chance of death each time you cast a spell from the eye. So you really want BOTH.

And check it out... regarding someone trying to destroy the items incorrectly:

You may try other methods, and they may appear successful. You'd be wrong, though. The artifacts reappear in some random place in the multiverse, waiting for the next person to cut off a hand or remove an eye and embrace the evil within them.