Quintessential Katana is a uncommon Artifact — Equipment card from Teenage Mutant Ninja Turtles (TMT), collector number 23. Current market price: $0.20 (foil $0.32), TCGplayer market prices via Scryfall.
Equipped creature gets +1/+1 and has "Whenever this creature deals combat damage, untap it and you gain 2 life." Whenever a Ninja you control enters, you may attach this Equipment to it. Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)