Jokes aside, there are two conclusions I can draw from this.
1. I'm guessing you would be able to hit more mobs with an attack. So let's say your attack only hits a mob in front of you. With this Bronzed Grendal card, you can now attack mobs that are also to the left and to the right of you (I really doubt your radius of attack would be that huge, but assumptions are awesome).
2. There is such thing as minimum and maximum damage. Fenia R9 card is Maximum Over Thrust, which reads "Gives you a wider range of damage (for hammersmiths only)." But then, that would kind of be a bad thing, as luck can make you do less damage than you normally do because of random damage range. So let's say you do 400~500 damage non critical to Fenia. With this card, your damage may now be 350~700 damage non critical to Fenia. Something like that.
They're both guesses, though. Go put it on and try it out. I'm willing to place my bet on number 2, though.