Maybe certain other Deathly Hallows symbols will now light up in Harry’s presence, especially if there is a lost storehouse of some sort with a similar mark.
If it doesn’t end up being important, it could just be whatever enchantment is on the Peverell gravestone that makes it recognize someone’s anti-Death resolve (possibly only if they’re a Peverell descendant) and recite the prophecy, pointed out in the narration so the reader knows where the prophecy was coming from.
Maybe certain other Deathly Hallows symbols will now light up in Harry’s presence, especially if there is a lost storehouse of some sort with a similar mark.
If it doesn’t end up being important, it could just be whatever enchantment is on the Peverell gravestone that makes it recognize someone’s anti-Death resolve (possibly only if they’re a Peverell descendant) and recite the prophecy, pointed out in the narration so the reader knows where the prophecy was coming from.