Not sure which you bolded out so I will take a guess and if I got the wrong ones you can redirect me.
The knee weaking is good. Its like a surge of lust that hits you and makes you feel a cross between aroused nervous and excited all at once.
I decribed the slow smile once before here Post 12. It was in a little bit of a different context but if you read the whole post you will be able to visualize it better.