Shouldn't this say "¿Los piernas son débiles?" I thought if you're referring to a part of your own body you don't use possessive words.
You don't if it is obvious whose legs you are taking about. If you are a doctor you could be talking about another person's legs
No because the word <<piernas>> is feminine so it would be <<Las piernas son débiles>>
Yes I was always taught that you used los/las instead of mi/mis - like in English. But yes you made the mistake of using los, when it should be las
Mis piernas son debiles los brazos son pesados ya espaguetis de mamá now I know "my legs are weak arms are heavy already Mom's Spaghetti" haha
Sometimes she talks so 'fast' like she eats the word wich makes it hard to hear.
That was my guess, but it turns out actual usage differs from the common En/Es root. Feeble/weak works, but disabled is discapacitado o deshabilitadas depending on the sentence structure.
so we are to infer that, because "son" is used instead of "están", this person's legs are not just temporarily weak, but the weakness is an ongoing condition?
Yes, pretty much. You'd use estar if the person saw the love of their life and their knees got weak, for instance. With ser, they are either physically impaired or just kept skipping leg day.
"Debilitated" might be a bit of a strong word here. Débil simply means "weak".