As I interpreted canon: Canon!Voldemort also didn't recognize the symbol. Inference: Grindelwald studied the Deathly Hallows particularly and thus learned that symbol, to use as his own. The Deathly Hallows in general are well-known enough to have sayings like "Wand of elder, never prosper" but not the symbol.
Plausible, I guess. I don't suppose you can give us any hints as to whether during Harry's investigation of the Hallows, he discovers that its symbol was appropriated by Grindelwald, leading him to decide that, Dumbledore being a deathist and therefore unlikely to divulge to Harry his knowledge of the Hallows, Harry should contact Grindelwald, the second-most-powerful wizard known to take an interest in that subject? (You did mention that one of your major purposes in chapter 86 was to update characters' states of knowledge, and in that chapter Harry lea...
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 96. The previous thread is at almost 300 comments.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system.
Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, .
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: