Heart-Piercer Bow is a common Artifact — Equipment card from Commander Masters (CMM), collector number 390. Current market price: $0.19 (foil $0.20), TCGplayer market prices via Scryfall.
Whenever equipped creature attacks, this Equipment deals 1 damage to target creature defending player controls. Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)