Sword of Kaldra is a rare Legendary Artifact — Equipment card from Mirrodin (MRD), collector number 251. Current market price: $19.26 (foil $80.68), TCGplayer market prices via Scryfall.
Equipped creature gets +5/+5. Whenever equipped creature deals damage to a creature, exile that creature. (Exile it only if it's still on the battlefield.) Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)