Ancestral Katana (NEO) from Kamigawa: Neon Dynasty, available at 401 Games Canada.

• Rarity: Common
• Finish: Normal
• Artist: Daniel Ljunggren
• Card Text:
  Whenever a Samurai or Warrior you control attacks alone, you may pay 1. When you do, attach Ancestral Katana to it.
  Equipped creature gets +2/+1.
  Equip 3 (3: Attach to target creature you control. Equip only as a sorcery.)