No, it's a TWO level difference. This is not the old AD&D games. It's DOS2. If you're equally proficient in both, there's no way a weapon two level highers could possibly do less damage.
It's hard to tell why. But the stats you see in weapon tooltip vary depending on which party member you're selecting. You have to make sure that the right person is equipping the weapon, and they have the right abilities for it (one-handed, two-handed, and so on).
Last edited by Try2Handing; 21/08/18 04:05 PM.