At some point I wanted to change default core git editor from Vim to Notepad++. There are couple of solutions how to do that. However, this:
git config --global core.editor "'C:/Program Files (x86)/Notepad++/notepad++.exe' -multiInst -notabbar -nosession -noPlugin"
works for me on Windows 8.1. By writing this short post here I may save your time in researching.