This is one of the Artist's Proofs sold by Stan directly to his fans at conventions.
"This is number AP of 400 copies of the hardcover edition ... each of which has been individually signed, numbered, and illustrated by Stan Sakai." It has a bound-in limitation page with an exclusive color illustration and Stan has drawn a small Usagi headsketch next to his name.
Collects Usagi Yojimbo Vol. 3 issues 53-60, plus a cover gallery, sketches, and story notes. Introduction by Jack Davis.
From the publisher:
Nothing comes easy for rabbit ronin Usagi, not even being a spectator at the planned duel between his former teacher Katsuichi and Katsuichi's rival Nakamura Koji. Before the duel even begins, Usagi becomes embroiled in a dispute between Koji and a local fencing school. Along the way, Usagi discovers a devastating secret -- a weakness in Koji's style. It's a secret that could save his teacher's life, but at the cost of his own honor. This 17th volume of Usagi Yojimbo collects issues #53-60, including the entire "Duel at Kitanoji" story, and a handful of other great shorts.