A reverse funnel conclusion gives the writer an angle to format their conclusion. Looking at the introduction, reverse funnel stipulates that it should be turned backwards and rephrased as the conclusion.
Since the conclusion brings the paper together and finishes the thought, reiterating the introduction to remind the reader of what was just analyzed or proved strengthens the argument and may possibly convince the reader of the writer's viewpoint.
Along with summarizing the paper's key points, a good ending quote could be added to the conclusion to bolster the argument even more. Be sure that the quote is appropriate for the piece and encompasses the general idea of the paper.