Why "sharpest" is used instead of "sharp" in here?
Native speaker’s answer
Rebecca
"Sharpest" is the superlative adjective of "sharp". It implies that something, in this case the words, is the most sharp, comparatively there is nothing sharper. "Sharp" in this cases meaning producing a sudden, piercing physical sensation or effect. So these words are so cruel, mean or nasty that they cause a physical pain. The use of "sharpest" gives emphasis and depth to what is being said. Ex: Give me the sharpest knife you have. Ex: I felt the sharpest pain in my side.