I've been testing with vanilla weapons and Miapi weapons, but with Miapi's:

• Melee ones don't seem to increase their damage.
• Ranged weapons show that the damage on the item has increased, but when testing them against enemies the extra damage does not appear.
• And as for armor, the reduced damage appears on the item, but I'm not entirely sure if it applies.

I added some weapons and bows in the configs like: "miapi:modular_dagger" and "miapi:modular_bow" to see if they worked this way, but still no change to the damage.