Wiktionary
a. (non-gloss definition: Honorific epithet used parenthetically to mark a beloved person as being deceased).
Usage examples of "of blessed memory".
My ancestress, Resmiranda of blessed memory, had killed the last known descendant of Tryblith with the great sword Excalibur.
Count Lavastine of blessed memory believed I was his illegitimate son and named me as his heir.
Woolworth (of blessed memory): store brands maintained and visible across the entire country.
The Jerusalem Man - of blessed memory - left this earth twenty years ago, taken up by God like Elijah before him in a chariot of fire.
The Milford Science Fiction Writers' Workshop (of blessed memory) was the best experience I have ever had as a writer.
Your grandfather of blessed memory rolled out a keg of whiskey and we all got rather drunk.