No, this doesn’t work at all! I already ranted about it last week, but I’m going to state again that there has been no evidence so far that Jocelyn actually taught Clary any runes. Jocelyn hated the Clave and everything that goes along with it. So why would Jocelyn teach her daughter? This especially doesn’t make sense, because Alec said that the knowledge of the Raziel’s runes isn’t passed genetically. Shadowhunters learn the runes one by one, gradually throughout their entire childhood.
So this is yet another sloppy ass pull on Clare’s part.
I have another question, why did Clary remember this rune right now? She didn’t use the rune to find a way off the roof, or to uncover the demonic motorcycles. I also have a feeling that we will never see her use this rune in the future. So why was this sentence even necessary? The answer is that it wasn’t. It’s just Clare fapping away at Clary’s supposed awesomeness.