wakizashi
A sword, similiar in design to a katana, wielded not only by samurai, but by "non-warrior" class people who were forbidden by law to wear a longsword. The wakazashi has a shorter blade than a katana, usually ranging from 12-23 inches in length.
Should a samurai's katana break in combat, or if the samurai needed an offhand weapon, he would usually carry a wakazashi as a back-up
wakizashi
Smaller blade used by samurai. It is usually about 18-25 inches.
The warrior drove the wakizashi into his opponent
wakizashi
A japanese short sword made similarly to the Katana in both looks and proscession when being forged. Carried by the samurai along with their long sword, the samurai were the only japanese residents to legally carry both the Katan and Wakizashi. A Wakizashi's size usually ranges from 24 to 28 inches with a usually 18 inch blade. It's smaller size made it useful for indoor combat.
A common name for a matching set of a Katana and Wakizashi is called a Daisho.