You have to read The Infernal Devices series to understand..... and those three books are even after the six books in the Mortal Instruments series lol..... don't forget The Bane Chronicles and The Shadowhunter's Codex (The only one I have yet to read lol)
Talented artist Cassandra Jean worked with Cassandra Clare, author of The Shadowhunter Chronicles (TMI, TID, & coming 2015: The Dark Artifices), to make a set of "Shadowhunter Tarot" illustrations depicting the characters from all 3 series! More are on CC's as well as CJ's Tumblr pages. (*this pic is linked to CC's)
From Cassandra Jean’s Shadowhunter Tarot — there were just so many requests for Simon/Izzy it had to be done. They take the Ace of Swords/Blades which can mean unity and breakthroughs. Also Simon is holding Glorious which is definitely worthy of being the Ace of Blades.