Spiked Armour for Labyrinth Lord

A player in a game I ran yesterday spontaneously asked if he could have spikes on his armour and shield. My response was "erm, I guess so", and that was that. He used the spikes several times during the adventure, including dealing automatic damage to opponents who were hitting him. It was all good fun, and it was only a one-shot, so I didn't feel it necessary to come up with any negatives to balance out the obvious benefits he was getting.

Having now had some time to consider it, I think something like the following might work as a set of rules for spiked armour.

Buying
Banded, splint or plate mail can be forged with integrated spikes. This increases the cost of the armour by 50%. Either small or large spikes can be chosen. Small spikes increase the weight of the armour by 5lbs and deal 1d3 damage. Large spikes weigh an additional 10lbs and deal 1d6 damage.

Benefits
The character can make damaging attacks essentially unarmed, by simply throwing himself at opponents in an attempt to impale them on his spikes.

When hit by an opponent using natural weapons (claws, fists, bite, etc.) the character's spikes have a chance of inflicting damage on the attacker -- 10% per point of the attacker's AC. This chance applies per round against foes with a grappling, grabbing, swallowing or constricting attack.*

Drawbacks
On a natural to-hit roll of 1 the character spikes himself, suffering damage from the spikes. This is in addition to the normal effects of rolling a 1.

On taking falling damage the character is also damaged by the spikes on his armour. There is also has a 10% chance per 10' of distance fallen that the spikes on the armour are destroyed.

In most civilised regions such armour is regarded as dangerous, vulgar and brutal -- a sure sign of someone who's looking to start a fight. The character may get into trouble with the law if he wears spiked armour in towns and cities.

Indulging in a nice heroic embrace with ones companions after a battle is not recommended. The spiked character may risk becoming a social outcast.

Spiked Shields
A shield covered in spikes can also be purchased, again with either small or large spikes. A shield with small spikes costs 20gp and weighs 15lbs. A shield with large spikes costs 30gp and weighs 20lbs. Spiked shields have none of the benefits or drawbacks of spiked armour, except perhaps the drawback of being regarded by law-keepers as a sign of a dangerous rogue. A spiked shield can be used to make melee attacks, dealing damage based on the size of the spikes. If an optional rule for two-weapon fighting is used, a spiked shield may be used to make an off-hand attack. When using a shield offensively it grants no AC bonus.

* Lambton worm yeah!

Armour shall be splintered

Inspired by a post over at The Omnipotent Eye, I got to thinking about the possibility of an expansion of the commonly used shields shall be splintered house rule. I'd considered something like that previously, but always thought that it'd just make low level PCs too powerful. However, as Andreas points out in his post, a big advantage of such a system is that it serves as a money sink, as damaged armour obviously must be repaired. And as a DM in D&D, money sinks always appeal to me.

So here's what I've come up with.

1. Any time a character is damaged in combat they can choose to subtract up to 3hp from the damage suffered, in exchange for their armour's effectiveness being reduced by as many points. This should be noted on the character sheet. (DM's discretion whether this applies to stuff like lightning bolts or dragon breath as well as normal attacks.)
2. Damaged armour can be repaired by skilled blacksmiths / leather workers, for a price. The cost depends on how badly damaged the armour is. Any armour which is reduced to AC 9 is beyond repair.
   

Costs for repairing armour (using Labyrinth Lord armour costs):
Studded leather: from AC 8 = 20gp.
Scale mail: from AC 8 = 40gp, from AC 7 = 30gp.
Chain mail: from AC 8 = 60gp, from AC 7 = 45gp, from AC 6 = 30gp.
Splint mail: from AC 8 = 65gp, from AC 7 = 55gp, from AC 6 = 45gp, from AC 5 = 35gp.
Banded mail: from AC 8 = 75gp, from AC 7 = 65gp, from AC 6 = 50gp, from AC 5 = 40gp.
Plate mail: from AC 8 = 400gp, from AC 7 = 350gp, from AC 6 = 290gp, from AC 5 = 220gp, from AC 4 = 150gp.

I think the system is simple enough that it won't cause a great impediment during play, the most complex part being the repair costs, which are irrelevant in the heat of combat. And I feel like it's not unbalancing -- it gives low level PCs a slight boost, but at the expense of money, which is usually a bit tight until 2nd level. Of course for higher level characters with a few more hit points to throw around, there's also a nice trade-off effect -- a short term reduction in damage taken vs a longer term reduction in armour class.