An intelligence check, DC 15 must be made when identifying these items, or else the drawbacks of the item will not be apparent or the item will be mis-identified as a beneficial item. None of these items can be destroyed or removed from one's person by conventional means.
The Black Gauntlet
An elbow-length, black leather glove that radiates powerful magic, the black gauntlet was worn by a mad king as he strangled his infant sons. It imparts a +3 bonus to damage dealt with melee weapons, but any time a natural 1 is rolled it instead causes the wearer to make a whirlwind attack against all adjacent allies. If there are no allies adjacent, then the wearer will instead attack himself.
A two-handed spear that often conceals itself by polymorphing into various kinds of pole-arms, the backbiter was used to injure a powerful priest in the early days of a major religion. The backbiter inflicts +10 poison damage per hit, but any time an attack with it misses, it instead causes damage to the wielder as though he were attacking himself.
A pair of man-skin boots that often conceals its appearance via illusions, the petitioner boots are made from the skin of ghosts from the afterlife. Any creature wearing the boots gains +2 speed and +1 AC, but loses all fire resistance and cannot gain or benefit from it while wearing the boots.
A belt woven of tanned gnomish scalps that hides its true appearance with illusions, usually appearing as a dwarven belt or something that adventurers will assume is useful. As soon as it is donned, the belt polymorphs the wearer into a gnome. The wearer becomes small, gains -2 Strength and +2 Constitution, and temporarily loses any ability score modifiers from his true race (or loses access to his bonus feat, if human), but because the wearer is not a true gnome, that's as far as it goes. When the belt is finally removed, the wearer reverts to his true form, no worse for the wear.
Ring of Limb Paralysis
A gold ring with some ancient writing on the inside that seems to want to be worn. As soon as one puts it on, the arm on which it is worn becomes paralyzed and useless. It resists magics that cure paralysis until the ring is removed via remove curse, though a particularly desperate adventurer might remove the finger on which the ring resides.