All characters in SE and SC has nicknames. Here's some explanation of why Sophitia got these nicknames.

Emotional Goddess

Sophitia's nickname in Soul Edge is "Emotional Goddess". This is reasonable as Sophitia does everything she does for her family and the ones she loves. Also from her quotes, you can see that she cares about others' emotions and she is fulled with those.
More info will come soon!

Renewal of the Vow

Sophitia's nickname in Soul Calibur is "Renewal of the Vow".