Totsuka no Tsurugi

The Totsuka no Tsurugi (十拳剣 Ten Hands Long Sword) is a mythical artifact said to have been derived from the King's Seal. It is said that its powers can pierce through a Hollows mask and destroy the darkness in them. For this ability the current Vizards search for this blade in order to purify them selves and restore their previous forms. It is said that it has the ability to seal a Zanpakuto into its sealed state, making it one of the strongest Zanpakuto known to Shinigami.

Trivia

 * Despite not pysically being a Zanpakuto, the Soul Society archives classify it as such