What would be the best place to obtain/farm Red Katanas?

I've decided on getting a Red Katana as my end-game item. Is there anyway I can easily obtain one every 20min or so? I'm a 77 sader, so I don't have the range or mobility to farm effectively :/
Where would I farm for it? Or what other ways are there?

 

Pepes at El Nath. Relatively large mobs, but shared with that white wolf mob.

 

Night ghosts at Showa they drop cape int 60 aswell and I've found more katanas there then at pepes