So I love the idea of an adventurer shattering their spear in the heat of combat and having to draw their trusty short-sword to keep the nasties at bay. Or someone snapping off an axe-head in the skull of an enemy. I like Logan Knight's notches rule a lot, but think it's a bit too fiddly for me - I really don't want to slow down combat, since quick combat is one of the great features of OSR games like LotFP. So without further ado, my simple version:
On a critical hit or critical miss, roll 1d6.
+1 if you're using a spear, -1 for great weapons. Your weapon breaks on:
|Masterwork||double sixes on 2d6|
Most stuff is well-made. Other qualities are available if sought, they are worth:
As an quick extension of the rule, you can try to attack other folks' weapons. Roll to hit, on a hit they roll weapon breakage but add your strength bonus to the roll.
This'll give folks a reason to have more than one weapon, a good chance of having to get a new spear or whatever after repeated heavy combats, and a reason to value high-quality items without needing enchantments. Plus the idea of snapping off a sword in some awful monster seems pretty awesome.
For those like me that wonder how long each will take to break on average: