Max Quintus (no costume bonus): 747 attack * 270% = 2016.9
Max Horghall (ditto): 657 attack * 280% = 1839.6 + debuff
Justice: 609 * 285% = 1735.6 + blind
So, no, Horghall and Justice don’t deal more damage. Base stats matter. A lot.
This isn’t saying that Quintus shouldn’t get a buff too, but saying that he’s worse than them after this doesn’t pass the sniff test.