Today’s second glitch:
Here’s a thing you need to remember about commas and em-dashes: If you separate part of the sentence with a comma on one side, you need to use a comma on the other side, too. The same goes for em-dashes; don’t separate part of the sentence with an em-dash on one side and a comma on the other.
There is no reason for slaves to be capitalized; it’s a common noun, not a proper one.
Ending two phrases in a row with the same word (workers) sound a bit clunky (especially since the next sentences has worked in it). Menial can be a noun as well as an adjective, so let’s drop workers in the last part of that sentence and just say and other menials.
When used to mean what it actually means (and I’m very much against using it otherwise), literally serves to clarify that something isn’t just a figure of speech. There’s no reason here to think worked to death may not mean just that, so literally is an unnecessary (and potentially confusing) word. Delete it.
Her slaves were graded from the academically capable, who were used as teachers and clerical workers, to household slaves and other menial workers. The most violent and uncooperative would be literally worked to death down in the mines or as galley slaves on ships.