Good evening.
I can't honestly recommend anyone pay full price for this plugin if that's all they need it for, and that's really all its capable of doing in its current form, unfortunately. When the VS team implemented their own dual wielding thing into their battlecore plugin, I would've taken this plugin down completely, if not for the people who'd already bought it. At that point, though I couldn't heavily discount it because that wouldn't have been fair to those people either.
I found a topic on the rpg maker forums for another plugin to add requirements to equips, an a poster in that thread has shown how it could be possible to use that plugin to limit what's in the off hand, based on the main hand.
Good luck.
~Ramza