A rather decent set, as it has great poison resistances for an attire that is not from the Healing Church.
The Younger Madaras Twin dons this set.
This set belongs to the Older Madaras Twin and, interestingly enough, can be found near the summoning spot for the Younger Madaras Twin, if players have joined The League and have the Old Hunter Bell.
There are some interesting details surrounding this Set:
A capeless version of this set is worn by the Yharnamites who roam the streets below the Abandoned Old Workshop. Something which is beyond odd as there is no explanation for them to wear such an odd attire.
Another interesting thing is that the Great Axe-wielding Executioners (found mostly in the Hemwick Charnel Lane by the Cainhurst monument) have a cape design that is exactly the same as the one that the Butcher Garb displays.