First off. I think staring too deep at the mechanics here, is bad, albeit, in frustration I can understand doing so. I've done it, and continue to do it. Thinking about the systems purely mechanically, is a poor form. So I think I'll rather than pointing at mechanics as they are. Point to some changes that can be made to improve realism. A lot of these were already made in a fantastic thread by Vera, by various people and by Vera herself.
But I concur with some of them. And I'll summarize here. Without delving too deep into mechanical thinking.
There are some weapons that should not be single handed weapons, and should in fact be two handed. Or at least not permit dual wielding.
These are logical to think about, and I won't bother listing them here.
The bonus is too uniform between weapon types. A knife being duel wielded shouldn't provide the same uniform bonus as a sword, or a big fuckoff hammer.
If the bonus' are different, then inequality of bonus' can exist without problems. Because asymmetric design will take over.
Two handed weapons don't have a similar bonus to compensate for their weightyness and the sacrifice of a free hand when using them.