Each line of the question provides a clue. A "halo" = round object, "rainbow" = multicolored, "tight noose" = thread tying it on, "knife" = a needle used to button it. "Grief of the Elephants" alludes to the fact that earlier buttons were made of ivory. "Holy, like the elements" alludes to the 4 holes /4 seasons/4 primal elements while "scar of my soft master" = button hole.