Best thing you could have done, based on what you described, is a fiberglass oversleeve. Fiberglass is much slower than graphite, you wouldn't have modified the action a bit. You would just need a thin section a few inches long and fit perfectly to the ferrule to repair. Slide it into position to ensure a snug fit, remove and bevel a downward angle on both ends to "blend". Glue into position, cleaning excess - let dry. Afterwards, simply wrap and epoxy - you wouldn't have been able to tell and I guarantee it would have held better than the rest of the rod.