It's the little things that bother me in game. Not fireballs, not weird gate magic, not eye shots with a short sword in a swirling melee against foes twice your height, not dragons and demons and piles of gold. It's the little things that feel like big things.
One of the big little ones for me?
Full-power shots against people on the ground.
I can't tell you how many times per session that someone says, "I chop that fallen guy's head off." It's often a Rapid Strike, so it's two full power hits against a guy on the ground, aiming to completely cut through his neck.
It seems like the single best move in the world for breaking your weapon.
Just picture a prone foe - you're going to hack his head off by swinging your sword or axe through his neck, into the ground.
It's not always the neck, though - it's sometimes limbs, the skull, just the torso. It's never restricted by the angle of the weapon or the body. People swing to hit fallen foes like Joe Strummer smashing his guitar, never worrying about any damage to their weapon.
When you want to break a stick, cut a rope, snap some old boards, or cut off part of someone's body, you really want two points of contact and the target to form a line between the two. If you wanted to decapitate someone, execution-style, you wouldn't put them prone on the ground, but rather put their head on a block. In game, though, it never happens that way. A foe on the ground is easier to dismember than one standing up.
I vastly prefer it when someone takes the time to reverse a blade and stab. Or says, "I don't want to hit my sword into the ground."
How would a rule be structured for that? This might be a good draft version:
Hitting Prone Foes
Hitting a foe that is prone on a hard surface can be risky. Any miss automatically hits the ground, inflicting equal damage on the ground and on the weapon that impacts it. Any critical miss suffers the listed results, and hits the ground for maximum damage, likely resulting in breakage!
In addition, any damage in excess of that needed to dismember a limb or decapitate a foe (i.e. killing via a neck attack) hits the ground, inflicting damage on the ground and weapon alike as above.
Crushing weapons generally handle this impact much better, and take only half damage (on a critical miss) or no damage (on a normal miss.) Overpenetration is not an issue for crushing weapons!
Another option would be to just force a breakage check on a miss or excess damage check:
Hitting Prone Foes
Hitting a foe that is prone on a hard surface can be risky. Any miss automatically hits the ground, forcing your weapon to check for breakage as if parrying a heavy weapon. Any critical miss suffers the listed results, and results in a breakage check.
In addition, any damage in excess of that needed to dismember a limb or decapitate a foe (i.e. killing via a neck attack) hits the ground, forcing a breakage check as above.
Crushing weapons are more resistant to breakage, and check for breakage only on a critical miss.
Either might work as a rough ruling until it was clear it needed to be either ditched or banged into better shape. I'm not sure I'd do this, but I'd feel better if I did. Downed foes are more interesting if you can't just say "I Telegraphic Rapid Strike to his Neck!" to make sure they are dead, not without risk to your weapons.