From the exception (see attachment), it seems related to xerces - possibly because we ship with a version and jboss with another. Goes in the direction of my feeling we shouldn't bundle this at all.
On surprising thing is:
01:14:43,764 ERROR [JBossContextConfig] XML error parsing: jboss.web/localhost/context.xml.default
— well, it looks like the infamous jboss classloader "issue", where the jars in the webapp seem to be used to load stuff which is outside.