Only ideas at this point.
In previous discussions the question has come up as to why anyone would use one weapon over another since their parameters are identical. Compare a Short Sword vs. a Dagger. All combat parameters are identical - cost for short sword is double+ the dagger cost and roleplaying wise you can conceal a dagger far more easily than a short sword.
In my opinion, why not say that a dagger gets a bonus to Init over the sword, both are equal on attack bonus, fumble chance with a short sword is slightly higher, but give a short sword a +10 over the dagger in terms of damage? The Main Gauche can then also be handled better as it gets reduced significantly in damage, but gains the higher parry bonus.
This may appear to add a lot of complexity, but as these are static modifiers that are applied whenever that weapon is used it is a worthwhile consideration (IMO).
Taken to an extreme (off the top of my head right now) you could do away with attack sizes and cover that entirely with these weapon bonuses. After that I'm not sure you need damage caps at all. And while I am still not sold on an AP methodology, if you wanted to allow weapon speed into the mix you could indicate that you get an extra attack for every 30 points of initiative. An initiative roll/result of 33 gives you 2 attacks. A roll/result of 61 gives you 3 attacks. Now that dagger with the higher init bonus becomes more desireable for the quick, unarmored combatant, while the heavily armored soldier takes the short sword and shield option. (Note - this is mostly off the top of my head and has not been fully thought through - so it may be absolutely flawed)