[Sawrock]

I'd like for it to be five ranks, with +1 crit per rank and +0.5 power per rank, doubled if the weapons don't match.

The reason why I'd suggest power over extra critical or parry chance is to appeal the kind of character fantasies that would use two weapons at once. The common one I think that most easily comes to mind is the dual swordsman, represented already by the Sarasha Gi (and which would make good use of this as well). The other kind of character that comes to mind though is casters- whether it's a dark mage with a dagger in their robes or a sword-and-spellslinger type. Yes, those kinds of characters can easily use the elemental spell ores, but if a mage wanted to include a tome for flavor they would appreciate the power to their tomes more than the critical or parry chance.

I do think with what you've wrote that not giving it hit does make a good contrast to using upgraded gloves (and can represent the clusterfuck that trying to use two weapons can actually be, although I am in no way advocating for hardcore realism).