Having a foul mouth and horns will prevent you from getting into Heaven where you would blossom into an angel. If you have horns, you are not meant for Heaven and will not blossom there. To blossom in Heaven, you must not have horns or a foul mouth.
You don’t want to blossom into a demon so you saw (さ) off your horns with a saw. If you saw off your horns, maybe you can beg for forgiveness and have your foul mouth forgiven.
Currently there are no similar looking kanji which exist in the WaniKani learning system