Katana

The Katana is a new close combat weapon revealed in Left 4 Dead 2. It kills Common Infected in one hit, (as seen in multiple game play videos) similar to other melee weapons. It has a much wider range than the any other melee weapon.

The katana is not really meant to be used against Special Infected, because using it on a Boomer would cover you in bile, and killing a Spitter would leave you right in the middle of the goo. Being used on a Charger, Jockey, Hunter or Smoker it would take time to reach them. Against a Tank or Witch it would probably do little damage.

Trivia

 * The Katana is the primary weapon of Japanese Soldiers known as Samurai.
 * It is unknown why the katana appears in places like The Highway, being such an antique weapon, unless a survivor brought the katana with him/her to defend his or herself.
 * Even though this is a long, bladed weapon that is more than capable of decapitation, you cannot decapitate a Witch with this weapon, only The Axe. This seems like a poor and short sighted move, since some would argue that the Katana would be better at witch decapitation than the Axe. This would probably overpower the weapon however, since its reach already makes it highly powerful.