Accorder's Shield is a common Artifact — Equipment card from Scars of Mirrodin (SOM), collector number 136. Current market price: $0.31 (foil $2.64), TCGplayer market prices via Scryfall.
Equipped creature gets +0/+3 and has vigilance. (Attacking doesn't cause it to tap.) Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)