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 learned that Grindelwald was held in Nurmengard, which Moody is partly responsible for guarding. This seems like a violation of conservation of detail if the information goes unused.)
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 learned that Grindelwald was held in Nurmengard, which Moody is partly responsible for guarding. This seems like a violation of conservation of detail if the information goes unused.)