Ok, I figured it out finally... I think.
To calculate the back row penalty, it is much more simpler than I thought.
For each hand wielding a weapon that is not back row compatible and the character is in the back row, subtract 32 from the current hit rate.
Examples:
Cecil @ level 1 with Legend Sword
99 + 0 (level bonus) - 32 (back row penalty) = 67% hit rate
Even with a multiplier of 2, he has a good chance of missing a target while in the back row (my attack algo will debut soon...)
Cecil @ level 99 with Crystal Sword (FF2US name) aka Ragnarok in FF4
99 + 24 (level bonus) - 32 (back row penalty) = 91% hit rate
The hit rate loss is almost negligible, but damage on average will be lower.
See how this hurts Edge... a lot.
Edge @ level 25 with his default katanas
(90+90)/2 + 6 (level bonus) - 64 (2 back row penalties) = 32% hit rate
The hit rate is atrocious, and arguably could be like equipping early game weapons.
Edge @ level 99 with the best katanas (90% Murasame, 99% Masamune)
(90+99)/2 + 24 (level bonus) - 64 (2 back row penalties) = 54% hit rate
On average, this means Edge will be vastly inefficient in the back row (it's not 50% damage drop because of attack power randomness, but still significant).
In sum, Edge needs to be in the front row almost all the time, unless you buy him some Boomerangs.
