[JR Jansen]

I would say go with longswords for dual wielding.
I don't think you can put proficencie points in weapons classes once the second class exeeds the first one. You merely get your stuff back but the remainder of the game you'll be playing as a mage. So if you want to dual to a mage and dual wield long swords, put as much proficencie points in longswords and dual wield. When you dual at level 9, you should be able to put 5 stars in longswords and 2 in dual wield. Then if you dual to a mage, put your points in something else. I'm playing right now as a fighter dualed to a cleric and have 5 stars in warhammer and 2 in sword and shield style and am kicking myself for not putting them in dual wield. Bah, anyway, i do have a very low AC so it's not that bad.