just to point out that when sheilds had reduced 'force feild effect' in earlier beta (or none at all. i forget) archers dominated, they could just hail spam arrows at aproaching infantry and regardless of the targets shield, he was going down.
the 'force feild' simulates the soldier intercepting the arrow with his shield, giving this to the player to control manualy would be rediculously hard, far easier to have it an automatic thing controlled by the character.