Arcanum Things is a rare Artifact — Equipment card from Mystery Booster 2 (MB2), collector number 508. Current market price: $0.15, TCGplayer market prices via Scryfall.
Equipped creature has flying. Equip {2} Equipment swap {2}{W} ({2}{W}: Exchange this Equipment with an Equipment card in your hand. If this Equipment was attached to a creature, attach the new Equipment to that creature.)