Cheapest priced copy (Mirrodin): $16.99 at Card Kingdom, near mint, their price list as of .
Sword of Kaldra 
Legendary Artifact — Equipment · Rare · Mirrodin · #251
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.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $16.99 to $34.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Mirrodin | 251 | Rare | $16.99 | $34.99 |
| Mirrodin Promos | 251★ | Rare | — | $17.99 |
One ruling from Wizards of the Coast
- 4 October 2004You exile the creature that gets damaged.