“One thing you can not fault Judaism for, is that we always spell out precisely what is d’oraisah, d’rabbanan, and chumrah. These halachos are spelled out precisely in the poskim.”
Poskim? Who actually asks pokim? Who actually reads halacha? Most people here get there psakim from the CR! And if the CR says it is assur diyoraisa to have elbows uncovered then it is! (Thank you Sam2 for refuting this)