Here is the “official” answer:
As Marybeth and Herman so nicely describe, it is fall
>It’s not who I am
>but my condition
>that is here the theme.
A planet in fall is in the sign opposed to where it is exalted.
Exaltation and fall are conditions. Either of strength, or as here, weakness.
>Those that I welcome
>are not in my esteem.
The sign where a planet is in fall does not esteem it,
nor do any other planets that receive it in the sign of its fall.
>It is their weakness
The planet is weak.
>With me they meet no favour,
>for they have lost their Eden
>and cannot climb away.
Just as exaltation is a condition of enthuastic love,
fall is a condition of being loathed.
>What am I? Tell me. Say.