Trollsmyth's Shields Shall Be Splintered rule to give the shield more value in melee is one of my favorite house rule ideas to come out of the OSR blogosphere.
It's easy, simple to employ in The Game, and makes sense to my way of playing. It also gives a bit more juice to combat. Like a saving throw, it allows for an exiting narrow escape from a possible nasty end.
I like to roll it around in my mind. It has a tasty texture and rule symmetry that appeals to me. Thank you Trollsmyth!
This is how I phrased the rule for my own houserule document.
Any player character, who is employing a shield and takes damage in melee combat, can opt to instead have their shield take the damage. The shield will be shattered and must be discarded thereafter, but the character takes no damage from that particular attack.
I like it so much, I want to share the terror and excitement of that near brush with death with PCs of classes which normally don't carry shields.
So, I'm extending the rule to include hastily improvised shields. Things which might be snatched up in a desperate attempt to ward off an otherwise fatal blow.
Items such as a stool, a chair, a saddle, a halfling, etc..
This way, magic-users and thieves, who usually need all the protection they can get, have a rule to give them a last chance to escape a cleft skull.
Of course, same as with the shield, whatever object the PC grabs to serve as a shield is destroyed if made to absorb the damage the PC would have otherwise incurred.
*regarding the halfling. Only NPCs may be sacrificed in this manner. PCs may not be employed as hastily improvised shields by other PCs.
Pics are a nice medievalesque stool I found online, and a clip from a larger sketch by the mighty Jim Holloway, one of my favorite D&D artists.