Alessio,
Thank you so much. You are right I added the following jboss-deployment-structure.xml to my /WEB-INF/ folder and essentially I have turned Jboss into a stripped down web application server by excluding all the EE features and allowing my WAR to contain Apache CXF 2.5.0 etc.
<jboss-deployment-structure>
<!-- For JBoss7AS and WS-Security to play nice must exclude the SAAJ jars -->
<!-- This is the top level ear module, which contains all the classes in the EAR's lib folder -->
<deployment>
<exclusions>
<module name="javaee.api" />
</exclusions>
</deployment>
</jboss-deployment-structure>