Why have my ranged units so low effects on advancing heavy armoured enemies?
To avoid the elimination of whole advancing AI amies by the players ranged units. The focus of Chivalry is melee combat. If you want your ranged units to be more effective try this: As defender use hills, arrows and bolts from above have an higher impact than those coming from the front. Archers should be ordered to fire on advancing unarmoured and crossbowmen on advancing armoured targets, but they are best used to shoot routing or retreating enemies in the back.