"Whenever you steal up on someone you had better an o-wakizashi short sword" - Natori Masatake (Shoninki)The wakizashi (Kanji: 脇差 Hiragana: わきざし) meaning "side inserted [sword]" is one of the traditionally made Japanese swords (nihonto) worn by the samurai class in feudal Japan. It was normally carried paired with a katana. It was worn indoors when the katana was set aside at the entrance. This is due to the fact that it's short length was great for close quarters combat. It was also favored by the shinobi.
According to both the Giyoshu military manual and the Shoninki shinobi manual, a shinobi could use a sword to help him climb by tying it's cord around his foot, propping the sword against the wall, and stepping on the hilt to climb over the wall or fence. The Shoninki mentions that one of the jobs of a shinobi is stealing the enemies' wakizashis.