Let's say an archer could shoot 10 arrows per minute, and the army had 500 archers. That would be 5000 arrows per minute, let's say the battle lasted 2 hours. And the archers were focusing fire on your formation of men. It was not ridiculous at all that over the course of battle, hundreds of arrows directly hit on your armor especially if you are standing in the front. Well yes a man can only carry so many arrows with him, but there were wagons and horses that could carry many more arrows, a horse archer army could bring wagons of arrows with them, encircle your men, dismount and start shooting. When they run out of arrows, just grab more. I said that it only took one out of five hundred arrows to seriously injure you, didn't mean that it actually took that many to break the armor. If you are unlikely the first arrow could end your life. I never said that armor was not effective, I am just telling you that arrows were quite effective as well. They were not just some weapon only useful against naked peasants.
If the arrows are actually like bullets in this game, most battles would last under a minute. Every arrow would be one shot kill, you won't need anything else, just archers. It took how many arrows for you to kill a ulfhednar? I played many hours of this game, and some archer units can be op, but not to that extent. What I would recommend is a better morale system and a weight system. Being shot at will decrease the morale of your troops, and more arrows stuck on your shield and armor, the slower you move. Decreased morale would increase the chance of being mortally wounded, and your troops might flee during the battle as well. Without these features, bows should deal more damage or they wouldn't be useful.