such system with add & subtract features exists in dungeon siege. items that are high on strength will have penalty of minus in magic/mana. something like that. it's good as this will be a balancing factor which will force thoughts on combo of wearable items which will reflect strategy.
Good call! They're doing that in
Deus Ex 2. For those who don't know,
Deus Ex is a FPS RPG where you're a cybernetic agent. You can upgarde yourself with bio-augs, providing new skills and abilities. In the second game, you can get some of these bio-augs on the black market. They have great benefits, but come with side-effects.
Something like this could be good if you're going to have 10 rings. Like janggut said, have a ring provide a benefit and a penalty. eg. +3 Strength and –2 Constitution. You'd still need to lower the stats of each ring. You can't have a Warrior with 10 rings of +3 Strength and -2 Intelligence. Warriors don't need Intelligence for the most part.
Personally, I prefer the idea of two rings. It's harder to mix and match them this way. You have to search for the perfect rings for you and make tough decissions, and not just get little bits here and there.
