Just like the description states - I'm looking for the darker (regular) Thieves Guild Armour. Not the Nightingale armour, but the cuirass the Brynljoff is wearing before he switches to the Nightingale. I'm still wearing the original suit and I love it, and the darker version just looks that much better. Do you get it when you are declared Master the the Guild, or is there a way to get your hands on it before that (without killing someone wearing it of course).

Thank you for the help, thieves and warriors alike!

I haven't seen it and I finishes the quest line for thieves.