A French version is available here.
Browsing again through the work of Sainct-Didier on Gallica, I randomly stopped on a hand-written page at the beginning, which suddenly caught my attention by this paragraph:
La Croix du Maine says that this author still lived in 1584 and is a descendant of Guillaume de St Didier gentleman of Provence, who composed a book on fencing in 1174 that is to say 400 years before this one
I was aware through Olivier Dupuis’s excellent transcription, that La Croix du Maine was giving some biographical information.
But this book on fencing from 1174? That was news to me, even though the first works on fencing history have no shortage of shady references and dubious parallels.
I have therefore traced back the reference, firstly in Les bibliothèques françoises [the French librairies] de La Croix-du-Maine et de Du Verdier, where it is indeed located (albeit without any genealogical claim, and without a precise publication date, the author just noting the funny coincidence in names):
Guillaume de S. Didier, Gentelman, born in the land of Velay, Provençal Poet, in the year 1185. […] He has written a very beautiful treatise of Fencing. He died in the year 1185, or thereabout*.
* See Jean de Notre-Dame, Chap.6
This Jean de Notre-Dame is actually the brother of the famous Nostradamus, who compiled The lives of the most famous and ancient provençal poets, in which can be read:
The monk of Montmajour says that this Guillaume sang with pleasure, but was bereft of love; put the Fables of Esope in vulgar Provençal rythm, and also did a beautiful treatise about fencing, dedicated to the count of Provence.
Now we get into more tricky territory with this “monk of Montmajour”. I have found articles claiming that this character never existed, and was basically only a literary device allowing Jean de Notre-Dame to flesh out his biographies. So the track stops here for the moment. I have not been able to find the source of Jean de Notre-Dame’s claim, if there has ever been one.
Remains this intriguing reference to what would be the oldest european fencing treatise known to us, predating the famous Ms. I.33 by more than 150 years. Who knows whether it truly existed or was just a figment of the imagination of Jean de Notre-Dame? Which HEMA researcher would not dream of discovering such a treatise?