Rules for weapons breaking is something I house-rule removed from my TFT game. My view is that game and house-rule designers tend to set the breakage probabilities too high, and that weapon-breaking rules should be limited to cases where a figure is using a weapon that's noteworthy for being cheap and shoddy (or improvised) or to cases where the attacker makes a "break weapon" or "sunder" called-shot attack.
Sunder - such a weird concept when I start thinking about it. It seems reasonable to attempt to break someone's weapon when you think about it. "Enemy have weapon. If break weapon, enemy not have weapon." Then I realize that there's an important reason that most combatants don't decide to break weapons: if you stop attacking your opponent, i.e. attack your opponent's weapon, you'll probably get stabbed and die.
So that leaves sunder attempts to combatants who don't have to worry about dying, like those following the rules of sport or game, or supremely unmatched opponents . . . but I digress.
For cheap and shoddy weapons where random-weapon-breaking rules make sense to me, my house rule is that the "your weapon breaks" results happen on a critical hit, rather than on a bad "fumble" miss.
When put in general use, weapon breakage rules do spice up combat - the way ground black pepper would spice up a slice of lemon meringue pie.
That's kinda fun. Make PCs pay for their double-damage. No free meals, right?
Yup. Weapons in my OD&D (1974) house rules can be damaged in combat. Any time that a hit is scored with a weapon on a roll result of natural 20 (i.e. a result of 20 on the die) or a weapon is used to parry against a roll result of natural 20, roll two six-sided dice. If the result of this roll is snake eyes (a result of two 1s), the weapon in question has been broken and needs to be repaired before it is good as anything other than an improvised weapon.
Sorry, gotta math this out . . . odds of a 20 roll, 1:20. Odds of snake-eyes, 1:36. Odds of a broken weapon on any single exchange, 1:720. Hmm, OD&D. Is that 1 attack per round, or did higher levels mean more attacks? With 1 attack and 1 weapon-enabled parry per round, that's 360 rounds, and with the urban-legend 5-round-average combat, that's 72 opponents (defeated, assuming no resurrections).
If a PC using my above module uses a two-handed weapon (d10) and always chooses to roll damage, he'll break the weapon (down to a d4) after a maximum (statistically) of 18 attacks. That's 6 all-out attack rounds, maybe 2 whole opponents.
I'd expect my non-master-forged, and affordable, weapon to last a bit longer than 2 opponents, but not quite through 72 opponents (or even 36, the more average result). We could use some common ground.
, my Oblivion character's weapons seemed to degrade down to 10% after each quest, and sometimes during each quest. Thoroughly annoying, but pretty reasonable given how much walloping I was doing. It makes me think that there's an important balance going on between fun, realism, and rate-of-fighting . . . It's funny that some people use "5-minute workday" with a bad connotation: if you're at war, sure, you can expect hours of fighting in a day. If you're not at war, 5 minutes of fighting is a horrible day, but you at least expect your weapon not to break during those 5 minutes.