Small

I wrote this info in another thread, but I also have new info.. the old info..
When a critical hit is dealt in a Bow+Arrow setup, the additional attack power added is the total attack power of the bow..
Normally, the basic formula looks like this:
Base Attack Power = Str/4 + Bow's Attack Power/2 + Arrow's Attack Power
When a critical hit is dealt, the forumula looks like this...
Base Attack Power = Str/4 + Bow's Attack Power/2 + Arrow's Attack Power + Bow's Attack Power
which can be written as..
Base Attack Power = Str/4 + Bow's Attack Power * 3/2 + Arrow's Attack Power
This matches up with the general critical hit formula of increasing the attack power by 50%, except it comes in the form of doubling the Bow's current attack power.
It suggests that Bows are the best at dealing critical hits.. which seems to be the case, because the most you can add is 127 attack power by the regular formula.. under this case, you can add up to another 255 attack power via the critical hit.
Also, something new..
For Edge, the critical hit bonus is basically picking the weapon that has the greatest attack power (Masamune in the SNES version, Mutsunokami in FF4A) and add 50% of that weapon's attack power. This would explain why Edge sucks at dealing critical hits.
This was tested against Edge equipping a Katana+Claw... as you know the Claw provides 0 attack power. It doesn't matter which hand the stronger weapon is in.