This is a very fun storyline! Well done!
Actually this raises an interesting question for me. Whilst we are on the subject of orders of knights.
A certain computer game, obvious the fount of true historical interpreteation & knowledge giving, has the 'Knights of Santiago' as an Iberian order. Knightly orders have never been a particular interest of mine so I am not too surprised I have never heard of them. Then again, I wouldn't be too surprised if they just completely made them up.
So anyone able to to enlighten this poor ignorant Englishman on that order, and indeed direct me to a good book (in English of course) if they did in fact exist.
The Knights of Santiago are indeed a legitimate militant order specific to Spain (Iberia).
I reccoment the book A History of Medieval Spain, by Joseph F. O’Callaghan. It has everything you seek conserning Hispanic History of the Middle Ages. I also reccomend Tribunals of Hermes: Iberia, the old ArM3 interpretationof Iberia. The book is a flawed gem, as I have stated again and again. One of my issues with the book (I have three of them) is the overly Infernal tone. An example of this is that they paint the Knights of Santiago as being corrupted by infernal powers.
Just like the rest of mankind! /2 Intrinsically corrupted, Fallen, and best not forget it.
I actually quite liked that bit. Any organisation with a degree of secrecy and mystique about it is ripe for Infernal corruption, and a corrupt militant order raises all sorts of wonderful possibilities. The in-character conversation where the Praeco chats comfortable about his conversations with the dedicated demon of Barcelona - that was going too far both in terms of excessive diabolical content and outright cartoon silliness.