I was thinking of a possible solution to the "armour vs swords" debate that everyone more than half of the people here might hopefully agree on: What if the resistance of armour plate was directly determined by quality levels?
For example: To pierce superior quality armour plate, you'd need to use a masterwork sword (2 quality levels above the armour), or an exceptional spear (1 level above), while to cut through it, you'd need an axe of equal or greater quality.
Maces would work at one quality level below the armour, and above, so superior quality maces would work fine against exceptional plate. Picks would work at 2 quality levels below, or finely-crafted, while hammers could work at 3 levels below = well-crafted.
Other weapons would have their own armour-penetrating qualities.
Halberds for instance might work at 5 levels below, making only artifact armour effective against them, while whips would probably never work against even no-quality plate.
Any lesser weapons impacting on greater armour might simply cause bruising/scratches and "fatigue damage". Ofcourse, if the weapon is being wielded by a titan, the crushing bruising could still be quite fatal, but this would be determined more by the attacker's strength than anything.
Considering the new way that weapons are handled under .31, this might be one of the better ways to differentiate between weapon quality levels, in terms of game mechanics.
The attack could still slide or glance off, ofcourse, but this would be determined more by the weapon skill of the attacker vs the armour-use skill of the defender, than the quality of the armour.
Materials would come into play by allowing the armour to become "damaged". Better weapon materials could cause more damage to the armour--even if the attack didn't damage the dwarf inside--which would reduce the armour's effectiveness over time, allowing even a dwarf in artifact HFS plate to be swarmed and eventually slaughtered, if you don't manage to defeat the attackers first. This "damage" could be very temporary, only requiring the dwarf wearing it to either hang it on an armour stand, or visit a metalsmith (to reduce micromanagement), while still representing the rigors of drawn-out battles.
Other qualities of weapons would remain the same, and other types of armour could have their own set of "steps" per weapon type.
Critical hits might simply ignore any armour worn--you "found a gap".