Bad self-esteem is, lol.

I think self-esteem and self-concept are linked almost as much as self-esteem and self-worth. Think about what "esteem" is: it's respect, honor of sorts given to someone because of something about them. At best, it's a lack of condemnation.

You honestly sound like someone with awesome, healthy self-esteem: namely that the things you're bad at don't bother you (though, you don't seem to value your strengths one way or the other...). It's just "I'm good at x, I'm not so good at z". No emotion. Totally foreign to me - being good at something (to my own standards where I could take others' comments seriously) would, I hope, give me new reason for self-respect, esteem whatever. It would imply, to me, that I am a useful, valuable person, I'm good for something, I'm deserving, etc.

By contrast, I eviscerate myself emotionally over the things I'm bad at: failure and inferiority mean I'm objectively useless, unlovable, maybe I don't even deserve to live if enough of it compounds. I dwell on things, I see no reason to try if I fail.

Your sense of self-worth seems to compensate for any possible feelings like this - you see yourself as good, worthy, etc regardless of flaws. As far as I can tell, that's self-esteem, or a good enough substitute. Maybe that's why it confuses you: most people only talk about it in the unhealthy sense.