That's impossible with the current technology. The only real options would either be to keep it exactly the same or weaken them while boosting the enemies morale through the roof so they will never run since an 'average' general is dogmeat to any unit worth a damn.
Just wait until you get Pikemen, sometimes I swear those guys have a baggage cart full of dead generals armor and banners drug behind them. 'Pikemen, gasp! I...must...charge!'