Trance makes you go into a trance for like ten seconds whenever you see something scary. Illusion of normalcy makes you look normal until you get in a fight. Boils make you less tough and agile because they hurt like shit all the time.>>62340417
Slaanesh wouldn't switch your gender, only add additional genders and genitalia/tits. However, you have to actively serve Slaanesh to get extra sexy bits.