Being in a rage is an idiom for being extremely angry. Alternate translation: "The king was extremely angry and got up" (See: [[rc://en/ta/man/jit/figs-idiom]])
Here seeing represents realizing or understanding. Alternate translation: "He realized that disaster was being decided" (See: [[rc://en/ta/man/jit/figs-metaphor]])
This can be stated in active form. The abstract noun "disaster" can be expressed with the more concrete verbs "destroy" or "kill." Alternate translation: "the king was deciding to cause a disaster against him" or "the king was deciding to destroy him" (See: [[rc://en/ta/man/jit/figs-activepassive]] and [[rc://en/ta/man/jit/figs-abstractnouns]])