By total and stupid luck, (I've found quite a few things thanks to that in my hacking attempts, actually), as i'm horrible with more technical stuff.
While trying to make sense of the debugger in Fceux some time ago, I was playing around with it and the game genie encoder while fighting when i saw these adresses:
By changing E6 for other value you can modify the defense (8395) and evasion (8397). I don't know how it works exactly (again, i'm horrible), but lowering to something like C6, B6 or A6 makes it so you don't lose defense or evasion. Seems you can't really choose what percent of defense you lose, it's just 0% or 100%, at least as far as I know with my insufficient skills. Changing it to D6 for example has no effect.
I didn't touch that again until recently, when I rememberd that STARWIN could look the Magic Multiplier in the rom, so I tried to look through the rom with a hex editor, and the offset is 683A5-683A8. E6 74 E6 52. I should have done it before, I know.
As you lose both entirely, what I decided was to mantain defense while losing evasion.
It makes some sort of sense as you're still wearing armor while you try to run away, but because the characters should be focused in running they don't pay attention to the enemies. Gameplay wise, You'll still be hit and more often at that, but at least damage will be partially reduced thanks to your defense.
I always found ridiculous how in a new game, goblins can cause you around 2/6 points of damage normally, but the moment you try to run away, those 2/6 transform into 2x/3x, sometimes even 4x points of damage pretty much killing you in one hit.
And that's just goblins. Add the fact that it's prone to fail, and you have get one big problem and a possible Game Over button if you don't know it beforehand.