Blade of the Oni is a mythic Artifact Creature — Equipment Demon card from Kamigawa: Neon Dynasty (NEO), collector number 89. Current market price: $1.07 (foil $1.56), TCGplayer market prices via Scryfall.
Menace Equipped creature has base power and toughness 5/5, has menace, and is a black Demon in addition to its other colors and types. Reconfigure {2}{B}{B} ({2}{B}{B}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)