What according to you are the toughest chapters, given that someone has cleared ST2, hence finds the ones relating to ST2 relatively easy.
I think that CA1 is less about "tough chapters" and more about the technique of answering exam questions. There will be some chapters that you're likely to be less familiar with (such as General insurance products and Risks in benefit schemes), but the material isn't technically challenging. The main target is to be able to generate a wide range of ideas.
