[Kelly Pedersen]

You're right, based on the description of the techniques, and the way Riposte works, there is an inconsistency here. I have no knowledge of fencing in the real world, so I can't say whether the description is actually accurate, but assuming it is, what I'd suggest doing is adding a new perk to the Italian School style, Special Setup (Ripost from main weapon after parry with off-hand). Basically, it does what it says - allows you to use a Riposte with your main weapon, with the appropriate bonuses, after taking the relevant penalties to your off-hand weapon parry.