Changing how damage is calculated which is currently assumed to be :
Damage dealt = A - D , A being the weapon's attack power and D being the matching defense
When attacking a monster with it weakness this leads to a constant of 60 points damage increase for weapon with attack power with twice the value of the targets defense leading to a higher damage out put for lower damage multi hit weapons (like blitz on fiend and beasts) than higher damage short combo weapons (Grandfaust alchemers and every other heavy weapon).
My suggestion a new equation for calculating damage
Damage dealt = A*[B/(1+ exp((-A+D)/40))+M]
Where A and D are the same as before B is a predetermined constant and M is the minimum damage ratio
So the part in the brackets is you damage "booster/ penalty" with a maximum damage boost of M + B and a minimum damage boost of M
This would work with damage of any size unlike the current system that has separate equations for low and high damage
I could plot that in a graph, or you could explain what it does, what the old formula does wrong, and what the new formula does better.