The sword card is a spirit who posesses people to become expert sword fighters. This happened in episode 8 when Sakura had to face an enchanted Rita who bought the sword card thinking it was a brooch. Without a host, the Sword Card cannot do anything but float around, vulnerable.

When it is used as a card, the power of the sword is bestowed on the summoning instrument. When Sakura uses it, it transforms her wand into the sword. The sword is also very sharp and can cut through nearly anything.