git-rebase-reword is a simple git command to change one commit (last or older) the same way as you ammend
It is named after the action on rebase interactive to ammend a commit "reword". See this post and git rebase man -section interactive mode- ##Install
Download and symlink to your path
$ git clone https://github.com/albfan/git-rebase-reword.git
$ cd git-rebase-reword
$ ln -s $PWD/git-rebase-reword ~/bin/
$ ln -s $PWD/reword_editor ~/bin/
##Usage
$ cd <repo>
$ git rebase-reword <commit|symbolic-ref>
# reword a commit
$ git rebase-reword b68f560
# reword a reference
$ git rebase-reword HEAD^
# reword last commit
$ git rebase-reword