I'm working on some story elements that may ultimately involve the fabled Rings of Verditius (or what appear to be).
What are some ideas of what they can do? In the Mystery Cults book they hint that they are either more powerful than any other rings, implying that the Founders were truly very powerful, or the rings are not very powerful, but can do something minor that Hermetic magic can't do (such as heal without vis), implying that they were people of vision and had some abilities that could not translate over into Hermetic magic, but not necessarily very powerful.
I'm of the opinion of a little bit of both with Verditius. Likely a poor spell caster but master enchanter, as well as having secrets he never shared with Bonisagus and that possibly were never able to be incorporated into even his House due to his untimely demise. So he might have rings that were either very powerful or able to break Hermetic limits.
In the end I believe I want the seeking more important than the having, and the items to be more of a plot device than a treasure to own. Some of the things I'm thinking:
Two or three of the rings become more powerful in proximity of the other, even dependent on the other and/or with this proximity their powers become greater.
One of the rings seemingly could break a Hermetic limit, that of true feeling. Verditius was a lonely magus...This seems weak, except for the fact that it can work. Imagine being able to instill true loyalty and/or love towards someone who has a powerful Gift (one of the only things holding them back from being truly influential in the world). This could be the ring that is truly the most powerful in that it can unite so many people. Perhaps also because it can break the limit, it is also able to get through MR easier (like ignoringg Parma, but not Form resistance or vice versa). One Ring to Rule them All...I like the idea of breaking this limit more than something more spectacular such as healing. A feat like this might even be overlooked by those who are power hungry but lack subtely and imagination.
I would keep it to just one ring being able to break a limit, if they all could that'd be a bit too much to believe.
Some other ideas?