delericho
Legend
- an evil wizard
- a mad wizard
- an incompetent fumbling wizard
All good.
Or it's left over from the Ancient Empire, and over that time the magic has degenerated and the item has thus become cursed.
Or the item belonged to a powerful and evil wizard, and when he was finally slain his hate was so powerful that it 'infected' his items which became cursed. (Of course, a particularly cruel DM could therefore introduce a %age chance that the villain the PCs are fighting now is going to cause a retributive curse on his items when he's eventually slain...)
Or the item is simply a trap for those who would rob from the tomb of the pharaoh. There's some precedent for that in the real world...