Looking at that deployment packaging and the exception stacktrace - I'm guessing that the jar in your .ear/lib/ folder is requiring a jar from the .ear/.war/WEB-INF/lib folder. The spec doesn't allow the .war classloader resources to be accessible outside of it. So you will have to move the dependent jars into the .ear/lib folder.
That's exactly what I did to make it work. Wondering if there's a way in Jboss to enable the .war classloader resources to be accessible to the EAR class loader.