The All Severing blade. It cuts through anything you want it to cut. And also your own hands. Make sure to have a healer on standby and use plenty of painkillers.

Collar of Commerece: +10 barter and gives canines the ability to understand commerece and run businesses, aflicts them with knowledge of economic exploitation and inequal power dynamics

Magic sword of infinite sharpness.

Sheathing the sword, or holding it by the hilt, quillons, or pommel causes it to become incredibly heavy.

Flaming sword. Only the handle sets on fire.

Amulet of speak with the dead - cursed. Once attuned the user can speak with the dead, but can only interpret chat with the living as wailing, any attempts to speak with the living will sound like wailing to the other entity. Removing the item does not break the curse.

And I'm stealing that idea for my game, and that one, and this one is cool too ...

a skill scroll but the skill is related to an unknown knowledge of FORTRAN. Those who have used similar scrolls in the past have lost their sanity mumbling about "transitive arrays" to an early grave. many scholars believe the scrolls to be a form of dark magic and a form of punishment against man and his hubris.

a tome of summoning but it can only summon fictitious characters from textbooks. characters like the ones portrayed in math books and the like. you can use them an unlimited amount of times but they remember everything each time they come back. it's a bad idea to summon them as fodder as they will eventually kill you out of desperation.

an amulet of perception, it really doesn't do anything but turn you into a conceited astrology hipster that always gives their opinion on how you need to "open your chakra" and constantly attempts to strike up sexual awakenings with the general public. it has a hidden trait that enrages anyone that's heavily spiritual or holy, temporarily turning them to evil.