The phrase ‘go in peace’ appears several times in scripture where that benediction proclaiming peace is as the Hebrew “Shalom”. It may have a similar intent as using the word “goodbye”. Goodbye is a contraction of “God be with ye” which conveys a blessing, like a prayer or hope that the other person will travel safely. I’ve read that to ‘go in peace’ used in the new testament may refer to the anticipated peaceful rule of Christ.