test it out for yourself. take the unit i said above and charge it into roman vigils, watch closer the damage you do, itll be equal to just hand to hand combat. Now edit the primary and secondary stats and place the number for charge bonus 40 or whatever it was in the primary charge as well. Now try again and charge the vigiles, youll see that when you charge home your initial impact will cause more damage(ie. the charge bonus). Its probobly that you werent looking closely enough to notice the charge bonus, if you dont use saka or the like you would probobly never notice