I've always liked karma being a part of the prayer system. The idea to use it on faith weapons is also really neat. But as someone that mastered all of the faiths over half a year ago, I have tons of karma piling up that I can't use. I think one of the only problems Runic has is the lack of things to do for people that have finished everything- from jobs to ranks (which won't be a problem for long), and to faiths.
Karma Ideas (though I'm not sure these make anything less complicated)
- I don't remember where I read it, but there was talk about possible faith shrines that people would build. Could karma somehow be plugged into that?
- I think I also read about players having multiple faiths at once. Perhaps karma could be used to unlock "slots" for faiths. Players have room for one active faith, and then unlock room for another using karma, and so on.