Since I made a similar thread in the other board (without actually spoiling anything).... and it got closed for not being "in the right place" and for "flaming" someone who was "trying to help me" [translation : I was sarcastic to someone who was being completely unhelpful]... (and one other reason which is supposedly forbidden to mention) .... I'm gonna ask here instead (since this is where I supposedly should have written it in the first place):

Can I still get a duplicate of the Nightingale Blade via ordinary in-game glitch or has it been patched?
And if so, how?
That is to say "how" in as much detail as possible.
I'm not writing another paragraph for this... I just want to find out how to get a second copy of the Nightingale Blade without people constantly hindering everything.