Bronze darts do not appear to be giving the extra physical (piercing) damage they are supposed to.
When I equip my character with either copper or bronze darts, the stats. ( as viewed in the character sheet ) are identical.
The stats do change when iron darts are equipped. (showing +1 damage and to AB on the character sheet)
I tried this IC with several different 'batches' of bronze darts, and Serrissa's character (Ferrit) also did as well, to confirm what I was seeing.