tantou
短刀 (たんとう, literally, "short blade" or "short katana")
A single or double-edged knife carried by Samurai in Japan or by Noblewomen for self-defense. The sides of the blade are nearly flat.
Early Tantous had no ascetic quality and were pure weapons, but up until the 16th century, the tanto was preferred to the wakizashi for use in battle by Samurai while a wakizashi was used for ceremonial occasions. After this period, they were used interchangeably. Can be used either for stabbing or slashing.