Shining Armor is a common Artifact — Equipment card from Throne of Eldraine (ELD), collector number 29. Current market price: $0.14 (foil $0.23), TCGplayer market prices via Scryfall.
Flash When this Equipment enters, attach it to target Knight you control. Equipped creature gets +0/+2 and has vigilance. Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)