I must be really lucky because I got the Kotetsu from the werewolves without chaining them. I hunted them from level 8-22 or so and somewhere in-between one of them dropped one.

I found it's best when you get to 22-24 to go to the dinosaur in estersand. he gives a lot of exp and if you do a 3 chain quickening on him and have the gladius or the kotetsu you either kill him with the chain or can easily finish him afterward helps to have all the HP augments as well. I stopped at level 27 though because I was getting bored and I wasn't getting the bone armor or helm and continued with the story. It's funny how easy like the firemane and mimic queen are when your level 27 but then you can get through it quick and get on with over-leveling.