I tend to be in favour of anything that increases the amount of tactical options that the player has, but in this case I worry that it might clash too much with the semi-realistic tone of the game. Dual-wielding pretty much didn’t happen outside of specific styles centred around it – usually using light weapons like Buce notes – and even then it was really rare. Mostly suited to something like a duel. This is because shields basically outperform a second weapon in every single way. Better defence, you attack with it just as well, protection from arrows, easier to use, can form a shieldwall, and so on. In case of a destroyed shield it would also be more natural to just start two-handing your main weapon, because you can’t actually protect yourself with a sidearm the way you can with a shield and you can do more damage that way. Not to say that it didn’t happen, it’s just that shields are amazingly useful.
There’s also the problem of implementing it in this action point system to reflect to above. It would either be too useful or something that you would only want to use for role-playing purposes.
I’m of the same mind in looking for ways to expand your options in combat, though!