Vulnerability really means to be strong and secure enough within yourself that you are able to walk outside without your armor on. You are able to show up in life as just you. That is genuine strength and courage. Armor may look tough, but all it does is mask insecurity and fear.
Detachment is being apathetic or aloof to other people, while un-attachment is acknowledging and honoring other people, while choosing not to let them influence your emotional well being. Detached would mean I do not care, while un-attached means I care, although I am not going to alter my emotional state due to your emotions, words, or actions.