Cheapest priced copy (Champions of Kamigawa): $12.99 at Card Kingdom, near mint, their price list as of .
Oathkeeper, Takeno's Daisho 
Legendary Artifact — Equipment · Rare · Champions of Kamigawa · #265
Equipped creature gets +3/+1.
Whenever equipped creature dies, return that card to the battlefield under your control if it's a Samurai card.
When Oathkeeper is put into a graveyard from the battlefield, exile equipped creature.
Equip {2}
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $12.99 to $37.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Champions of Kamigawa | 265 | Rare | $12.99 | $37.99 |
One ruling from Wizards of the Coast
- 1 December 2004Oathkeeper's second ability checks whether the card's creature type is Samurai, not whether the creature was a Samurai when it left the battlefield.