Mr. Peters,
I do not "title myself" but do hold such qualification. That is Master-at-Arms, or Maestro, which is an accurate and granted title indicative of my chosen profession in Life - Teacher.
This is not proudly paraded or flaunted. You may note that I sign simply with my name.
As for my proficiency in teaching or ability, if you doubt it, test it.
A man may be measured and known not by his claims or titles, but by his proficiency and abilities. A wise man knows this of any other before judging him.
I do hold a title but make no claims, and can only leave it to others to pass judgement on my professional proficiency and abilities either knowingly or unknowingly.
If you are interested enough to form an educated opinion of my teaching and martial abilities, you are welcome to meet with me in Edinburgh at my Academy or at any workshops I may be teaching.
Master at Arms is a title which is earned. It is not simply an adjective that describes your profession. "HEMA instructor" or "Teacher of swordsmanship" describe your profession, but "Master of Arms" is something that needs to be earned, tested, and proved.
I will gladly test your ability the next time I am back in Scotland. But even if I do, it doesn't really mean anything. At best, it will give us an idea about who is more skilled, but that's meaningless without a wider context. As someone able to evaluate other people only based upon whatever knowledge, experience and skill that I possess, I cannot hope to accurately gauge whether you would have warranted that title in the historical context in which those arts came from. In other words, I have no knowledge of the skill of specific medieval and early modern masters by which I can compare and evaluate you. So really, the whole exercise is meaningless save for determining which of us has more skill.
The point here is that no one- and I mean no one- is qualified to judge someone as worthy of the title of Master of Arms or Maestro. None of us having any standard to judge it against save by our own interpretations and reconstructions of historic European martial arts, as flawed or accurate as they may be. We can make judgments about skill, (but only from within the context of our reconstruction), and that certainly isn't enough to know if someone warrants the title of "master" or not. There may very well be individuals in the HEMA community who would have been considered "masters" had they lived in the medieval or early modern era. But without some way to evaluate them beyond our current abilities, no one has a right to use that title.

