A quick look at sword_1.5.9-8ubuntu1.patch reveals that the only change made in Ubuntu was modifying the maintainer field to match the Debian-Maintainer-Field Spec. This change can be safely dropped in order to perform a sync.
Here is the portion of sword_1.5.9-8ubuntu1.patch that shows the changes in debian/control:
diff -pruN 1.5.9-8/debian/control 1.5.9-8ubuntu1/debian/control
--- 1.5.9-8/debian/control 2008-03-17 09:21:01.000000000 +0000
+++ 1.5.9-8ubuntu1/debian/control 2008-03-17 09:14:25.000000000 +0000
@@ -2,7 +2,8 @@ Source: sword
Build-Depends: autotools-dev, quilt, patchutils (>= 0.2.25), cdbs (>= 0.4.27-1), debhelper (>= 4.1.0), libz-dev, pkg-config, libcurl4-gnutls-dev, libclucene-dev
Section: libs
Priority: optional
-Maintainer: Daniel Glassey <email address hidden>
+Maintainer: Ubuntu MOTU Developers <email address hidden>
+XSBC-Original-Maintainer: Daniel Glassey <email address hidden>
Standards-Version: 3.7.2.1
Package: libsword6
If you read the changelog you will notice the word "Fakesync" which means "manal upload, just changing the changelog entry (and maintainer field)" - this is necessary when for example the .orig.tar.gz between Ubuntu and Debian differ (md5sum differences are enough). It might worth finding out why it's necessary and do a fakesync.