Can having a bad grounding situation destroy a circuit breaker?
Sounds to me like a coincidence. 

Grounds have nothing to do with the functionality of a circuit breaker. Meaning a circuit will work properly (albeit less safely) with or without a ground. The ground is a "safety backup" in case of a short circuit to metallic parts and pieces.

Hopefully all the work you did on the sconces is proper. Did you install and mount boxes for the wiring and to mount the lights?