Lifting the hand represents trying or daring to do something. Alternate translation: "who tries to change ... or to destroy" or "who dares to change ... or to destroy" (See: [[rc://en/ta/man/jit/figs-metonymy]])
The abstract noun "decree" can be expressed with the phrase "what I have decreed." Alternate translation: "to change what I have decreed" or "to say that I have decreed something else" (See: [[rc://en/ta/man/jit/figs-abstractnouns]])
The phrase "hereby issue" means that Darius, by speaking, is issuing the decree. Your language may have a different way to show that the speaker is claiming to make something happen, not simply explaining what he is doing.