I'm new to this so sorry if I do this wrong but I just read this part and felt I had to share.
In the fourth book, while Josh is still under Mars' control he touches the table with all 4 swords on it and it says, and I quote:
"Particles of ice sparkled across Excalibur (Not a surprise) and red-black smoke drifted off Clarent (Again not a suprise); gritty brown sand formed on Joyeuse's blade(so that's the sword of earth), and Durendal's surface rippled as if a chill breeze were blowing across it(the sword of air!)."
YAY! My first post! The end.