Combat & Tactics for 2e did a similar thing where weapons particularly designed for armor penetration got +1 or +2 versus certain armor types (designated as plate, chain, and leather IIRC). You also had the really good penetrators just ignore X points of AC that came from armor: firearms ignored all/5/2 points at short/medium/long range, crossbows ignored 5/2/0 points, and bodkin arrows 2 points at short range.
The problem with that sort of thing in D&D is hit points. In reality, most hand-held weapons are perfectly capable of taking out another person on a good hit. Armor is meant to reduce the likelihood of such a good hit, and weapons develop to counter said armor. But in D&D, combat is a matter of attrition, so it's more important to do Big Damage than getting a minor attack bonus.