What are effects of physical and emotional abuse in a relationship? And what can be done to allieviate the effects?

I have 2 friends both were in abusive relationships. one went through mandated counseling and it seemed to improve their self esteem and view on life. The other feels that they are not different as aresult of the abuse. Although insecurity and poor self esteem may be a result of something else is there any advice that I can use to improve this persons self esteem. Or what are some of the things I could expect to encounter when interacting with these friends?