In the game 'Kohl Team', my paladin found the necromancers shelter in a ruin. He wore it for a while and then dropped it on the ground. It was then picked up by my dreadknight, who put it on. When I inspect the dreadknight's equipment, it says NaN after the symbols for chaos defense. At one point the words 'undefined' were superimposed over the symbols.
The same item is acting up in another of my games, Erythia8. This time a paladin found the item in a ruin, and did not trade it to another hero. Still says NaN where it should say -5.