I learned Eskrima from Sonny Umpad. Sonny was, and is, a huge influence on how I teach.
More than a couple of his students have called Sonny's style or training method their Rosetta Stone. I had the same experience. Training with him made many concepts and ideas fall into place, in Eskrima and in other martial arts. Many hypothetical 'what ifs', become 'ah, I see'.
But still, he died too young, the training left hanging as though there was so much more to do and see. We'll never know if there was a 'complete picture' or just an endless series of progressions and refinements, but that's OK, fitting even, as a legacy of how he was as a man.
I personally think he sits in the genius category with a mind perfectly suited to his obsession, which was to study the arts of his homeland. Don't get me wrong, the man was no saint, and he was certainly no role model for health and happiness, but he was a singular human being, hugely talented, humble, generous to a fault, massively creative, smart, focused and patient - Wow was he patient! Not having any Eskrima friends to play with, he started to teach so as to make some for himself! He wanted to create skilled practitioners that could push him so he too could keep his skills up. What a fabulous motivation.
So what made him a superior teacher?
Well apart from just being a very interesting person, he was highly skilled, obviously, and moved with an uncommon grace highly unusual in the field - this quality in particular drew people to want what he could do.
He was also eternally fascinated by the art of teaching itself - How will the student get this concept? Does this work? How about this? Ah, that worked ... but will it work on the others ..?
He understood the psychology of fighting really well, he saw patterns of behavior and individual traits he could use to put points across depending on the personality of the student, and encouraged students to play with each other as much as possible to see what the combination of personalities brought out.
In the Transmission post, the comments section brought out some commonalities other folks have found in great teachers. Apart from the emotional connections mentioned before, great teachers tend to push their students to perform at the edge of their abilities, great teachers do not spoon feed but encourage independent thinking, inquiry. They critique and expect high levels of performance. They also have a passion for what they do, and gain satisfaction in seeing their students improve.
Sonny had all of these, though perhaps his greatest insight, and most useful in terms of learning to fight/duel was the constant feeling he created in his students (and certainly in me) of constantly standing on the edge of chaos, of uncertainty, and the looming abyss of failure .... OK, that might be a bit dramatic, but I think that this emotional aspect of the training was a key component of why it was so effective.
Life is uncertain after all, decisions may or may not be 'correct'- I hate to say right or wrong, perhaps 'easier path' and 'more difficult path' would be better descriptors, so training in that same emotional space is very valuable as that is where 'stuff' is going to happen.
He understood this, perhaps not in so many words, but came to realize that it created a most efficient way to teach Eskrima.
Playing/teaching in the chaos, close to the edge, but not over it, is a skill in itself. It involves personal, one on one time, understanding the student and being able to read how they are faring. Sonny was great at frying your nervous system one day, but keeping you encouraged enough to keep going, giving you glimpses of the possibilities, but keeping you from becoming too obnoxious when you thought you had something.
He wanted you to see through his eyes, through mirroring his movement, flowing with him, defending yourself against him, watching him play others, trying what you'd learned whilst he watched.
It's very old school. Like I said, one on one, a systemless, troubleshooting approach with the individual as the focus.
In my opinion it's a highly effective, and possibly the most efficient way to learn, like an apprenticeship, not sure if it's for everyone though. Sonny has some really good students, some not very good ones, and many drop outs. The lack of structure, and the constant uncertainty was too difficult for some to handle, though of course others thrived in it, and the ones that spent the most time in it, are the ones that got the most out of it.
Just as a side note, from the teaching end of things, I've always said that I thought Sonny connected fighting to teaching through his interest in learning how to figure people out. His ability to disappear, blend, lead and trap was truly phenomenal. All these he could do so well because he was a superlative study of people, and he used these skills both dueling and teaching. I think he saw them as sides of the same coin - one constructive, and one destructive, and as a natural fighter, this is what kept him so engaged and creative in his thought, and teaching, process.