Any item may be cursed which can be determined by the DN and its effects that can be opposite of its magic description and bonus. DN could add flare and other details.
Cursed items usually hide their true nature until used or worn, and the DN decides when and how a curse reveals itself. A character can only be affected by one curse at a time. If another curse is applied, the stronger curse takes over and the weaker one ends or becomes dormant, as the DN decides.
Curses can be removed through many means: specific spells, rare potions, powerful blessings, magical items, rituals, or enough time under the right conditions. The DN determines which method applies based on the story, the strength of the curse, and the needs of the adventure.