Functionally the combination is just a readability thing yea? It didn't actually change any functionality in the game?
Previously, because of how the stat was worded, an attack with a mace while using a dagger in the off-hand would benefit from the "Damage with Ailments from Attack Skills while wielding a Dagger" stat, but not the "Damage with Daggers" stat. Now, none of that applies to the Mace hit.