Sitting on the throne is a metonym for ruling as king. AT: "the king who rules the Israelites as David did" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The word "sword" is a metonym for war. The sword, famine, and disease are spoken of as people who can obey Yahweh's command to harm the Israelites. AT: "I am going to punish them by having them die in war, from hunger, and from illness" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-personification]])