The Masamune is a rare Legendary Artifact — Equipment card from Final Fantasy (FIN), collector number 264. Current market price: $1.04 (foil $1.47), TCGplayer market prices via Scryfall.
As long as equipped creature is attacking, it has first strike and must be blocked if able. Equipped creature has "If a creature dying causes a triggered ability of this creature or an emblem you own to trigger, that ability triggers an additional time." Equip {2}