The Blue Flame of Vengeance. This story was originally written in 1929 and featured Solomon Kane. Howard failed to sell it, perhaps because it had no weird element, and hence Weird Tales would likely not take it. Howard rewrote it in 1932, changing the hero to Malachi Grim, changing the title to Blades of the Brotherhood, and shortening the story by a couple of pages. There is no record to show to which magazines this story was offered, if any. 

John Pocsik rewrote the story adding a weird element that was published under this name. Subsequent publishings of the REH-only version, use the title Blades of the Brotherhood, which was originally the title of a story featuring Malachi Grim. An earlier REH draft of The Blue Flame of Vengeance was titled The Blue Flame of Death.

The variant featuring Malachi Grim first saw publication through the REH Foundation in a transcript format in September 2007, and later appeared in the book Pirate Adventures in 2013. Additionally, John Pocsik adapted the Solomon Kane version, incorporating a supernatural element, and it was published in Arkham House's Over the Edge anthology in 1964.