Emasculation happens when 'feminine behaviour' in men removes pervieved power and agency and makes them feel degraded. Bare in mind, weakness is considered a feminine behaviour.
What removes power and agency from women is not us displaying masculinity, it's having our gender and sex used against us and/or against our will.
So being percieved as overly emotional/unstable, sexually promiscuous, not capable of intelligence or leadership, etc. and being raped and physically manhandled.