Have him come, have him see, have him conquer.

I once had a dull/uncharismatic/langurous Epeirote general who ended up becoming one of the best FMs I had at the time by keeping him in nonstop battle all across the Italian pennisula. By the time he gained the "Seen The Elephant" trait he had six command stars and the good attacker trait.

His victories gained him lots of influence and by the time the Romans were kicked out of Rome all he needed was management skills.