Re: Fen!
Fen actually isn't that much older than Gansey. She's totally happy to befriend him.
Fen can go into huge detail about Fillorian swords. As well as some of the most powerful magical blades (all made by her family) including the Leo Blade, a weapon powerful enough to kill a god/master magician, and the King's Sword, a sword designed to help magicians cheat and have the skill of a master sword fighter, though it only works for a magician high king...
...Which would be Margo, now. Huh. Fen hadn't thought of that.