Shard of Broken Glass is a common Artifact — Equipment card from The List (PLST), collector number SOI-262. Current market price: $0.11, TCGplayer market prices via Scryfall.
Equipped creature gets +1/+0. Whenever equipped creature attacks, you may mill two cards. Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)