Playing the UI, offline. Edison rulings. Blackwing Armed Wing’s effect is “If this card attacks a Defense Position monster, it gains 500 ATK during the Damage Step only, also inflict piercing battle damage to your opponent.”
It attacked my set Exploder Dragon. It’s effect is “If this card is destroyed by battle and sent to the GY: Destroy the monster that destroyed it. Neither player takes any battle damage from attacks involving this attacking card.”
I took the full piercing damage and both cards were destroyed as per Exploders effect. My understanding is that you do not take any battle damage, piercing or not and i cannot source any ruling that says otherwise.
Regards