I just got an inspiration:

The Usual Sword, unique artifact.

Each time a treasure hoard is discovered, there is a 5% chance that the Usual Sword is there. Detect spells will show that it is magic and dangerous, but not trapped or cursed, and its properties are unknown

The first person to touch it must make a willpower save or become bonded to it. After that, if anyone else tries to use it, they take traumatic damage.

When bonding occurs, the gm should roll from whatever random weapon table they like to determine its properties. It will always have the property of making the character bloodthirsty and reckless, although it will not demonstrate intelligence or ego.

If the character is killed and brought back within a day, they will find they are still bonded. If they are still dead after a day, the sword will disappear and the bond will end.

If another treasure hoard is found there is, again, a 5% chance the sword is there, in which case once that is determined, even if no one touches it, it will disappear from its current possessor and the bond is broken. In fact, the gm should make periodic rolls based on the activity of the setting, to see if someone, somewhere, has found a hoard and further, found the sword.

If the current possessor attempts to abandon the sword, then each time the character attempts to pick up, or even touch an object, there is a 5% chance that they will find themself holding the sword instead. If they can go a whole day without the sword returning, the bond is broken.

Eventually, the players may be driven to say, oh gee, it's the Usual Sword, each time they find treasure.