tons of good ideas, i'd like to point out my thoughts on the "stats" of all types of rings or even bracelets of this kind would be balanced in a way that you would not want to use more then 2 on any 1 crit, wearing 4 on a mage for example would drop ac to 0 and dex reduction on to. wearing 1 would be however a gain, 2 a risk, 3 and 4 totally not worth it.
some exceptions could be made of course depending on the type of ring or bracelet, con and charisma for example would not need to be heavily penalized.
initial thought was for items to be extremely rare drops from existing monsters that are easily accessed, cg, malok, sk, aet'thol for example.
If staff gave a ya or na, i could come up with hundreds of balanced ideas. No point putting to much effort into it right now though.