Hello,

just a quick question: I'm playing IWD2 and noticed that my barbarian (see screenshot) has an attack roll attribute modifier of +3; but since his strength is 18, shouldn't that be +4? He's wielding a melee weapon. The party has no current effects (and it's the same when I strip all equipment off him).

I do play a modded game, so it's maybe that - but I just want to make sure I'm not overlooking something obvious here?

Seems that way although you should also check attack rolls in the combat log.

Maybe you're wielding a 2 handed weapon?
If so then the Strength = (Str modifier)*1.5
In your case:
Strength = +4*1.5
Strength: +6