i killed myslef 7 times to get my world to pure black so i have a better chance of getting chunks and if lucky a pure bladestone, i have killed everything in 4-1 and 4-2 and all i got was 13 shards of bladestone and the rest were souls remains its bullshit, if anyone is around the lvl 37 and wants to trade or help add me and let me know my psn name is p1mpnutz43

i also have a lvl 155 character so if u have someone in that range im willing to dupe or trade  too

You will need to keep world 4 pure black.
 
Go to 4-2
 
Farm either the hidden black skellie (near beginning) or the BP black skellie (start at end).
 
FOR A WHILE!!
 
I prefer the hidden skellie b/c it allows you to stop by the cave downstairs to farm ephemerals (as long as you killed Urbain that is). b/c who can keep from staying online forever to keep the world pure black for days on end.

It takes a long ass time to get the pure bladestone, I got mine from the skeleton in the hidden passage near where you first meet the first Grim Reaper. The thing about that skeleton is that Luck doesn't count on it's drops so it's always just the luck of the drop, but it's still very low. I made a 5 Sharp Kilij out of it :D I already have a Tearing Uchi anyway and I like Kilij's better because they're faster. 
 
I would let you see my Kilij but I'd have to get to know you first, so you don't run off with it.

i know a glitch so that we can dupe the weapon so we can both have it n i can share my stuff with u too what lvl r u, my psn name is p1mpnutz43 get back to me if u can thanks