Hero's Blade is a uncommon Artifact — Equipment card from Commander Masters (CMM), collector number 391. Current market price: $0.30 (foil $0.29), TCGplayer market prices via Scryfall.
Equipped creature gets +3/+2. Whenever a legendary creature you control enters, you may attach this Equipment to it. Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)