Through most versions of AD&D, fighting classes are better off grabbing heavy armor and a two handed weapon than trying to go the sword and board route. Since I'm spicing up combat, I'd like to give the shield a little love and help justify why someone would sacrifice greater damage for just a measly -1 AC bonus. Note, neither of these ideas are mine, but they are both great.
Shields Shall Be Splintered. Upon a successful attack, a defender may sacrifice their shield to avoid the damage from a blow.
Shield Wall. A shield wall may be formed by 2 or more combatants wielding shields and single handed 3' weapons. Any combatant with a shield wall ally immediately to his right gains an additional 1 point bonus to their AC.
I like this implementation of a shield wall. A shield is carried in the left hand, so you need your ally to the right to protect you and continue the cohesion of the shield wall.
Note that any weapon that has the Ignores Shields traits is unaffected by both of these shield traits. A shield may not be sacrificed to absorb a blow nor does the shield provide any AC bonus whether in a wall or otherwise.