DISREGARD THREAD; INNACURATE
This was born of the assumption that damage bonuses were multipliers. This is not true. I'm leaving this here as reference to the conversation, should anyone be interested.
Currently, flourishes receive split damage bonuses when hitting a weak monster, but get pure damage penalties when hitting a resistant monster. I just noticed it; you guys should probably change something about flourish damage anyway... but that's another story.
Heyar's some proof:
Numbers from wiki, d28, first hits of combos.
Callahan does 131 damage against regular targets, 225 on bonus. 225/131=1.717
Callahan does 131 damage against regular targets, 38 on penalty. 38/131=.290
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Combuster does 203 damage against regular targets, 292 on bonus. 292/203=1.438
Combuster does 203 damage against regular targets, 135 on penalty. 135/203=.665
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FF does 203 damage against regular targets, 285 on bonus. 285/203=1.404
FF does 203 damage against regular targets, 47 on penalty. 47/203=.232
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So the penalty for flourishes is .232 compared to the .290 from callahan. The bonus is 1.404 compared to 1.438. You don't have to be a rocket scientist to figure this one out.
I also tested wiki numbers at d19 in my first test; they were accurate. I noticed that damage bonuses and penalties increase by about one half over the course of that time... which seems interesting to me, though it doesn't have much to do with the suggestion.
Edit: oh, sorry I cannot read x)