Complex sentence: The head bagman, Silas, stares down Swearengen as he curses him out-who backs down when Silas makes it clear he did not know what were the contents of the letter.
Split into simpler sentences: The head bagman, Silas, stares down Swearengen as he curses at him. Swearengen backs down when Silas makes it clear he did not know what were the contents of the letter.