Get the sword branch configuration up-to-date.
drush config-export
git add ../config
git commit -m 'Updated config from sword branch.'
Switch to master branch and pull in any changes.
git checkout master
git pull --rebase
drush updatedb
drush config-import
Go back to the sword branch and merge in changes (assume no code conflicts) from the master branch.
git checkout sword
git merge master
drush updatedb
drush config-import
Get the sword branch configuration up-to-date.
drush config-export
git add ../config
git commit -m 'Updated config from sword branch.'
Get the master branch up-to-date and merge in changes from the sword branch and get config in-sync.
git checkout master
git pull --rebase
git merge sword
drush updatedb
drush config-import