They already exist - get to 1000 Seven Bridges reputation and you can buy them.

The OP is probably looking for something better, the ones you get after obtaining 1000 Seven Bridges reputation only boost by 10% while taking 6% from own health (Minor orb of Fearlessness) which is a very minor gain. It's only 4% beneficial. Granted every bit counts, but when there are orbs out there for melee attack that do far better. The most basic damage booster in shop for melee attacks boosts by 40% (no negative effects), I think that there should be something more potent for spells as well, you use them far less often and have to build up to use them.