I'm working on giving the shield a bit more love in my Moldvay/Cook/LL hack. The shield really doesn't get the prestige it deserves. There's a reason it was a staple of the infantryman's gear from the dawn of history all the way into the 17th century. Shields work. They stop blows, they can be moved to intercept attacks coming from almost any direction, and they can be used to attack your foes. Simply lowering your AC by a mere point is hardly representative of the value of a good shield.
However, things are complicated by my adoption of some popular houserules for weapon damage. To whit, I'm considering tossing the plethora of different dice types for weapons and just adopting 1d6 for single-handed weapons and 2d4 for two-handed weapons. This is a variation on schemes I've seen elsewhere. Fighting with two weapons allows you to roll 2d6, and you take the better roll.
So you can see that there's a lot of value to fighting without a shield in improving the damage your character dishes out, making the shield an even less likely choice. What can be done to rehabilitate the shield and make it a worthwhile choice mechanically?
I'm considering allowing the shield to act as ablative armour. One thing historical shields frequently did was shatter. A strong blow with an axe or a sword could cleave a shield, splintering the boards. Viking duels often had a three-shield rule, allowing each combatant to enter the contest with a shield on his arm and two spares in reserve. (I believe this was seen in "The 13th Warrior", but it's been a while since I've watched it, so my memory could be faulty.)
With my houserule, you get the usual -1 to your AC with a shield. However, any time you take damage, you can opt instead to say your shield absorbed the force of the blow. The shield is shattered and must be discarded, but you don't take any damage from that hit. It's quick, it's easy, and it's valuable.
What about magic? Should a shield ward you against the ferocity of a fireball or a lightning bolt? My instinct is to say yes, but that makes a shield incredibly valuable, and takes a lot of the sting out of those spells. Maybe you can sacrifice the shield in exchange for an automatic save and half damage? Do you get to decide after you've rolled the save, or do you have to choose before you roll? We can go crazy with this and say that shields crafted from the wood of the rowan tree can be sacrificed for a successful save versus any spell, even those that don't deal damage directly.
What about magical shields? I'm kinda meh about the idea of mundane swords being able to shatter magical shields. On the other hand, I certainly don't want a warrior being able to just ignore hits every round because his shield won't break. Maybe each +1 gives the shield a 10% chance to survive the blow? Maybe I just won't have magical shields in my campaign? Seriously, in the quarter-century-plus I've been playing D&D, I think I can count the number of magical shields in my games on one hand.
(I also considered allowing the shield to give its bearer an AC of 3 versus a single opponent, but then you have to keep track of who it's been used against, and the character's AC jumps around between 3 and whatever their armour grants. It's a lot more hassle in the thick of dice-rolling. And I just love the visceral feel of shields being cloven in twain under the blows of a dangerous foe.)