>"It was a dark, stormy night"
This is a cliche. Delete it instead of try to acknowledge your use of cliche by adding "… as they say."
Who are they anyway? Bad Authors?
> "Violent strokes of lightning pierced the black sky."
The clause is redundant. You don't have to say the sky is black because you already said that it was a dark night. You don't have to say there is lightning because you already said it is stormy.
>"Opulent mansion…."
>"… appeared dead."
Lazy use of adverbials. Show, don't tell.
>"In her other hand…"
Four words that don't mean anything since we don't know what the other other hand is. Use "left", or "right", or omit the phrase.
I can go on and on. The editor might be able to correct the grammar mistakes, but even if you fix all of that the example will still be bad.