Probably it would be better to have a list of effects instead of mere two possible effects. Same goes for Defence amount and Defence damage filter. With this the same item could have multiple effects and different protection for different damage types.
There also should be an “Offense amount” and an “Offence damage filter”. And we also should be able to specify the amouts for “Defense” and “Offense” not only as a value but additionally in percent. That way we could define that a wood monster can withstand water by 50% but is affected by fire 200%.
Btw. how can we use the “Defense filter” now? I can give an item a defense filter but cannot assign a damage type to a monster. It should be possible to assign damage types to actors for offense and defense and to define the effectiveness for the damage types.