There's a nice Katana by Area-50, at Sharecg:

http://www.sharecg.com/v/33710/View/11/Poser/Katana-Samurai-Sword

Used that one, with some BB shaders, in the Geriatric Ninja Doris render in my gallery...

I'm working on an "Enter the Old Dragon" render featuring Doris now.

It'd be good to get that GND4 one in a set at some point... will look out for it.