It ignores 3 points of the enemies' armor. So if you're fighting with someone who has 12 armor rating, it'll be like you're fighting with someone who has 9 armor rating.
are you sure? the way it says it I think it might just damage them for exactly 3 health points, no matter their stats and resistances.
I'm not sure, but it seems like the most likely effect.
1. It's a magical weapon.
2. It ignores armor, IOW armor bypass.
100% armor penetration resulting in minimum 3 pts health damage per strike.
My fawourite weapon. Easy to get, extremly low weight and useful DMG after upgrade.
Fine for spell-sword players or if you need lower your weight.