Here's what I came up with in my homebrew campaign. Instead of appling a tedious aspect to weapons, we developed a feat.
Weapon versus Armor [General]
You can exploit the advantage that certain weapons have versus armored opponents.
Prerequisite: Base Attack +1
Benefit: The listed weapons receive a +1 to hit against opponents wearing armor. You must be proficient in the weapon to receive the bonus. You receive the bonus with ranged weapons only in their first range increment. You receive no bonus versus opponents who are carrying a shield, have natural armor or magical defenses, etc. but are not wearing light, medium or heavy armor.
Qualified Weapons: Crossbow (heavy), Crossbow (light), Falchion, Flail (great), Flail (light), Flail (heavy), Halberd, Hammer (Gnome hooked), Hammer (light), Mace (heavy), Mace (light), Morning Star, Pick (heavy), Pick (light), Sling (bullet), Sword (bastard), Waraxe (Dwarven)
Special: A fighter may take this as one of his bonus feats