Oni Blade Farming?

I've been trying to farm an Oni Blade alot lately.. Haven't had any luck at all.
I was farming three groups of Oni near Gyala hatchery. I got countless gold Oni Daggers, but not even one Oni blade.

Am I just extremely unlucky or are there better spots to farm it?

Any tips?

You can also farm shiro'ken

I've had a lot of gold oni blades drop for me while doing the Deep, as there are plenty of oni. Shiroken also drop them.

I bought a 15^50 oni blade for cheap from someone who claimed that he farmed them in Raisu Palace (NM or HM).

alright, cool.. Thanks guys.