I understand what you're saying Jona, but you have to remember, this game barely scratches the surface on full plate armor. I agree in that swords should just bounce off of Gothic Plate but Warband's engine doesn't work like that. However, have you ever seen what it takes to kill people like Firebus (lol) while using a Heavy Bastard Sword? Yes it damages him every hit which is silly but it takes easily 15+ hits as where a Bar Mace would end him in ~3.
I think you are simply over exaggerating swords' effectiveness. Why, I'm not sure perhaps its a lack of experience in using them. Now before you say I'm "defending" swords because I'm a 2h build, don't. I have over 20 gens experience in this game with around 7 of them being 2h and 5 of them using 2h swords. I've done 4 gens of 1h using a sword or a pick. Pick was my favorite, actually. Various cav builds, most polearm, and 5 gens of pure polearm, using a German Poleaxe exclusively.
I've said all of that to say this: I do not believe, considering Warband's engine and the timeframe majority that this game is based in, that swords are "OP". Nor do I believe that auxiliary weapons are "under powered". Having extensive experience with every class possibility in this game, and having used every weapon type extensively I believe I can say this, without bias.