I'm thinkin of doing something which would be kind of a translation from some other CRPGs I've played. I am partial to oriental influences, so let me know what you think.

A Kensai dualed to Mage at level 15.

9 proficiency slots for weapons. I'm having difficulty deciding how to assign them, as my character archetype used both a Staff AND dual Katanas as his main offense. In this other CRPG, skill with weapons was determined independently, and there were no style bonuses or penalties...

I'm leaning towards Staff Grandmastery with 2 stars in Two-Handed Weapon with 2 stars left for another weapon (or 2), or maybe go 3 and 4 with 2-handed swords and Staff.

My main question is whether that extra attack from Two-Weapon Style will be a large factor...?

I had a friend who made a character just like your type

proficient in staff and katana

anywayz, I dont understand your question, but as a Kensai/mage, you can take care basically everything (with or without weapon proficiency, lol)

in fact, all dualed classes involve mage is good