http://www.ninjaencyclopedia.com/weapon/manriki-gusari.html
I've taken the liberty of attaching a link to a general description of the weapon and an over view of how it was used. I could think of several ways to stat out the weapon, all of which sound good.
Suggestions?
If you must use a written weapon, nine section whip. Otherwise a spiked chain that does blunt damage.
Good call. Along the same lines as I was thinking. I'll write it up and put it in my campaign docs.
I am unsure if making it one handed and dropping the dmg to d6 would be better.