I do feel the character options presented would be perfect for a "Forge of the Artificer" style Ravenloft book. The Gothic Dark Fantasy vibes are strong.
Oh, also, what resources can you draw on? Fizban's Treasury of Dragons has a lot of material that would fit this this to a T, bot Draconic items and dragon hoard special magic rules, and Book of Many Things has some fabulous potent magic items.
The Dexk of Many Things itself would be pretty funny.
Axe of the Dwarvish Lords is always fun.
Who is the BBEG?
What are the details of the Revolution brewing? Would Orbs of Dragonkind contribute to fueling the confluct?
Who are your players characters? Are there any signature items that would turbocharged each one, like a Vorpal Halberd?
Fair take all around. It is a very "Old School" Sci-Fi story.
The novel had one of the more fun tie-in ephemera at the time of release, they actually made the Msth monk music:
OK, a little digging suggests that the formal answer ia that the Sea of Fallen Stars developed salinity in a similar manner to the Caspian Sea over millenia. Water flows in, but the only way it gets out is evaporation, so over time minerals build up.