Ther are a couple of important concepts to consider here.
The first is the importance of personal experience as a basis for teaching a martial art that you intend to have actual combative applicability.
The second is the nature of that experience and whether it's relevant to what you are teaching.
In the case of your TKD instructors, even if they had actual military combat experience in a warzone, they almost certainly were not using their TKD in that context. They weren't hitting enemy soldiers with spinning hook kicks to the head on the battlefield. So even if they are both stone-cold killers, it doesn't necessarily mean anything about the validity of what they teach in TKD.
Likewise, even if your BJJ instructor was an IBJJF world champion, it doesn't mean he would have a clue of what to do on a battlefield.
"Self-defense" is kind of a weird category for anyone to claim extensive experience in. Professionals who may have to regularly engage in violence (LEO, CO, bouncers, soldiers combat athletes) typically have different experiences from each other and from civilians defending against a predatory attacker. Anyone who has lots of experience in physically fighting off muggers must be badly failing the most important aspects of self-defense (awareness, lifestyle, target hardening, avoidance, de-escalation, etc).
I think what you can look for in validating yourself as an instructor might be the following:
One way is through feedback from people who do have more fighting experience.
I've never competed in MMA, but I trained with and occasionally helped coach professional MMA fighters and have gotten compliments on my skills and what I teach. Doesn't mean I'd be a good MMA fighter, but it probably means that what I'm teaching is solid from a MMA perspective.
I've never competed in boxing, but my boxing coach is a Golden Gloves champion, a 2x state champion, and has coached professional fighters. I asked him for guidance on being a better boxing coach and now he has me share coaching duties in class, points me out to his students as a technical example, and has me cover his classes when he has a schedule conflict. Doesn't mean I'd be a great boxer, but I trust that he wouldn't do that if he didn't think I was teaching things correctly.
I've never competed in wrestling, but some of my training partners and students were collegiate wrestlers. Whenever I teach wrestling techniques in my BJJ class and one of the wrestlers is there I usually pull them aside and ask them to let me know if I'm showing anything incorrectly. Generally they tell me that I've taught it correctly and occasionally even let me know that they've learned something new from me. Doesn't mean I'd be a good wrestler, but it gives me confidence that the elements of wrestling I teach are technically correct.
I've never had to take a knife away from someone in real life, but when I posted my video on dealing with weapons on the ground, I got some approving feedback from people who have done that. I never want to find out whether I would be successful in pulling that off in a real encounter, but that feedback makes me think I'm not leading people astray.
Another way to judge the validity of what you teach is by comparing it to what you see work in real life beyond your personal experience. I try to teach material that I see work in as wide a variety of contexts as possible - MMA, boxing, Muay Thai, Judo, BJJ street fights, and at as broad a spectrum of skills levels as possible. If I see video of something working in street fights, in high level MMA, and in beginner BJJ, and if I understand it well enough to pull it off in sparring myself, then I figure it's probably valid.
Another way is to isolate those elements of what you teach that you can fully pressure test without putting yourself through experiences that might damage your long term health. I don't know whether I ever had the mental attributes to be a professional fighter. I certainly don't have the physical attributes. And even if I did, I probably wouldn't want to risk the long term brain damage that is an occupational risk. But ... I've spent enough time grappling to know that only a very small percentage of the population can hold me down on the ground and choke me out - and those who can have both a high degree of skill and superior athletic attributes. I'm very confident that the skills I teach for defending oneself on the ground work consistently in a wide range of contexts.
Another way is to look at what your students achieve. I've never been much of a competitor, but some people who started out in my BJJ classes have gone on to do well and have earned their own black belts and surpassed me in skill. I can't take all the credit for that, but I'll claim just a little smidgen of influence on what they've accomplished.
Finally, I'll reiterate the importance of being honest about the limits of your knowledge and ability. I don't claim to be able to kick the *** of everybody who steps onto my mat. I just claim that I can point them towards becoming a little better at taking care of themselves. Occasionally I'll teach a technique that I'm not particularly good at (due to my body type, movement style, whatever) because I think it's an important technique that lots of people do use effectively. In those cases, I'll state up front that I'm not the best person around to demonstrate it, but I give them the best technical details I know and tell them to try it out, because it might end up being something that works much better for them than it does for me.
Hope that helps.
The first is the importance of personal experience as a basis for teaching a martial art that you intend to have actual combative applicability.
The second is the nature of that experience and whether it's relevant to what you are teaching.
In the case of your TKD instructors, even if they had actual military combat experience in a warzone, they almost certainly were not using their TKD in that context. They weren't hitting enemy soldiers with spinning hook kicks to the head on the battlefield. So even if they are both stone-cold killers, it doesn't necessarily mean anything about the validity of what they teach in TKD.
Likewise, even if your BJJ instructor was an IBJJF world champion, it doesn't mean he would have a clue of what to do on a battlefield.
"Self-defense" is kind of a weird category for anyone to claim extensive experience in. Professionals who may have to regularly engage in violence (LEO, CO, bouncers, soldiers combat athletes) typically have different experiences from each other and from civilians defending against a predatory attacker. Anyone who has lots of experience in physically fighting off muggers must be badly failing the most important aspects of self-defense (awareness, lifestyle, target hardening, avoidance, de-escalation, etc).
I think what you can look for in validating yourself as an instructor might be the following:
- Experience in actually applying the material you teach against resisting opponents (whether that be in sparring, competition, self-defense, wherever)
- Experience in teaching others who are able to apply that material against resisting opponents
- Feedback on what you teach from others who have experience in the domains of application that you would like your instruction to apply to
- As much information as you can gather about the contexts in which you have not had the opportunity to apply your skills, so that you can determine what elements of your material might need to be modified in those situations
- The humility and honesty to admit up front the limitations of your experience and knowledge
One way is through feedback from people who do have more fighting experience.
I've never competed in MMA, but I trained with and occasionally helped coach professional MMA fighters and have gotten compliments on my skills and what I teach. Doesn't mean I'd be a good MMA fighter, but it probably means that what I'm teaching is solid from a MMA perspective.
I've never competed in boxing, but my boxing coach is a Golden Gloves champion, a 2x state champion, and has coached professional fighters. I asked him for guidance on being a better boxing coach and now he has me share coaching duties in class, points me out to his students as a technical example, and has me cover his classes when he has a schedule conflict. Doesn't mean I'd be a great boxer, but I trust that he wouldn't do that if he didn't think I was teaching things correctly.
I've never competed in wrestling, but some of my training partners and students were collegiate wrestlers. Whenever I teach wrestling techniques in my BJJ class and one of the wrestlers is there I usually pull them aside and ask them to let me know if I'm showing anything incorrectly. Generally they tell me that I've taught it correctly and occasionally even let me know that they've learned something new from me. Doesn't mean I'd be a good wrestler, but it gives me confidence that the elements of wrestling I teach are technically correct.
I've never had to take a knife away from someone in real life, but when I posted my video on dealing with weapons on the ground, I got some approving feedback from people who have done that. I never want to find out whether I would be successful in pulling that off in a real encounter, but that feedback makes me think I'm not leading people astray.
Another way to judge the validity of what you teach is by comparing it to what you see work in real life beyond your personal experience. I try to teach material that I see work in as wide a variety of contexts as possible - MMA, boxing, Muay Thai, Judo, BJJ street fights, and at as broad a spectrum of skills levels as possible. If I see video of something working in street fights, in high level MMA, and in beginner BJJ, and if I understand it well enough to pull it off in sparring myself, then I figure it's probably valid.
Another way is to isolate those elements of what you teach that you can fully pressure test without putting yourself through experiences that might damage your long term health. I don't know whether I ever had the mental attributes to be a professional fighter. I certainly don't have the physical attributes. And even if I did, I probably wouldn't want to risk the long term brain damage that is an occupational risk. But ... I've spent enough time grappling to know that only a very small percentage of the population can hold me down on the ground and choke me out - and those who can have both a high degree of skill and superior athletic attributes. I'm very confident that the skills I teach for defending oneself on the ground work consistently in a wide range of contexts.
Another way is to look at what your students achieve. I've never been much of a competitor, but some people who started out in my BJJ classes have gone on to do well and have earned their own black belts and surpassed me in skill. I can't take all the credit for that, but I'll claim just a little smidgen of influence on what they've accomplished.
Finally, I'll reiterate the importance of being honest about the limits of your knowledge and ability. I don't claim to be able to kick the *** of everybody who steps onto my mat. I just claim that I can point them towards becoming a little better at taking care of themselves. Occasionally I'll teach a technique that I'm not particularly good at (due to my body type, movement style, whatever) because I think it's an important technique that lots of people do use effectively. In those cases, I'll state up front that I'm not the best person around to demonstrate it, but I give them the best technical details I know and tell them to try it out, because it might end up being something that works much better for them than it does for me.
Hope that helps.