The soldiers on the walls that had long enough ranged attacks from that distance used their magic to attack the back of the enemy's battalions after Branden gave them the order to do so. However, after traveling three hundred meters in the air and in an arc to avoid their allies, it was unavoidable that they would lose some power. Some of the enemies were hit by those and slowed down a bit, but soon, they became wary of the attacks and avoided them entirely.
While that was happening, several humans had their weapons and shields broken by the sheer power of the enemies' punches. They were almost at the level of Rain's punches when he used Iron Fists.