For spellcasters. This will appear as a metal skull cap, usually too thin to act as a helmet (GM's option), but often worn by wizard types as a form of head protection. It will radiate magic. It will also display that it is cursed, should that be detected for.
When a spell-casting individual places this upon their head, the cap will become anchored, incapable of being removed. What's worse, it becomes highly magnetic, drawing any and all ferrous metals (iron, steel, etc.) within a 10 foot radius in toward it.
Weapons will fly out of sheathes, tools jump through the air, and climbing spikes tear through bags, all aimed directly for the wearer's head. Cutlery, pots and pans, and even nails in rotten wood will fly at the wearer as they pass by. These things hit as if a 10th Level warrior were attacking, and at a +4 to Hit and Damage, due to the magnetic nature of the skull cap. Weapon damage is as normal. Damage from odd items is as the GM sees fit.
If a ferrous metal weapon is being wielded by the wearer or another character within the area of effect, they must roll a Saving Throw just to hold on to it. If successful, and they are attacking someone else, they do so at a -4 penalty to Hit and Damage since the weapon is being drawn in another direction. If they are intentionally attacking the wearer, they get a +4 to Hit and Damage on top of any other bonuses.
A high level Remove Curse will allow the skull cap to be taken off, whereupon it will cease to be be magnetic until the next victim comes along.
Image: England (?), 17th century - "Secrete" or Skull Cap (Hat Lining) - 1916.1895 - Cleveland Museum of Art by The Cleveland Museum of Art, released under a Creative Commons CC0 1.0 Universal Public Domain Dedication, and modified in Inkscape by David