The Hands of a Priest must not Shed Blood?

An aquaintance of mine, an army vet with a black belt in some Eastern school of martial arts, has mentioned that he has become interested in early Western martial arts. Apparently so are these people. They say:

We have centered our studies on two main documents. The first is based on a manuscript, owned by the Royal Armouries, named I.33. This document outlines different concepts of self defense as taught by a Priest to his Student. This document was written between 1280-1300.

The martial arts site says, "Please check our Sources section for more information." The Sources section says, alack, "under construction."

Interesting that a priest is the teacher. No creampuff clerics, here. I know the crusades had various armed priests, like Alleumes of Clari who single-handedly frightened most of the defenders of Constantinople to abandon their posts in the inexcusable misadventure that was the Fourth Crusade. Supposedly priests bearing arms has always been against canon law. (See this section of Aquinas' Summa.) I doubt teaching self-defense falls under this prohibition, especially since I have visions of a boxing priest from some black and white movie--Going My Way, perhaps--who teaches a boy how to fight. Speaking of movies, if these manuals lend themselves to well-choreographed fight scenes a film based on a medieval Western martial artist could make a good action flick.