Cursed Blades are a new sword added in 5.3, they are currently dropped by Wither Skeleton Bosses. Wither Skeleton Bosses only drop one sword per fight to a random player. Cursed Blades can be repaired with Perfect Diamonds or with another Cursed Blade.
When used, there is a 50% chance to inflict your opponent with the Wither Effect along with a 2% chance to inflict the user with it.
Cannot be crafted.
Obtained from killing the Wither Skeleton Bosses.
Cursed Blades can also be obtained by trading with villagers.