This looks like a limitation in the maven war/jar plugin (I assume that's what you're using).
As far as workarounds are concerned, I would suggest having a look at https://docs.jboss.org/author/display/AS71/Class+Loading+in+AS7 , in particular the section on using a custom jboss-deployment-structure.xml for setting the module dependencies.
Modifying the org.jboss.ws.cxf.jbossws-cxf-client module.xml is also going to work (of course it would affect any other deployment you declared that dependency in), but of course you changes are being overwritten if you upgrade jbossws.