With the Crazy 88 Yakuza gang as her personal bodyguard, O'Ren was able to carry the Shirasaya mounting of her sword, which she used to protect herself against assassins. The absence of a Tsuba distinguishes this mounting style, which was usually used to carry or store blades when they weren't going to be utilized for a while (the hand guard between the hilt and the blade). Katana has always been one of my favorites, so I'm happy to see her make an appearance in Left 4 Dead 2.
