For this one approach would be to use Interceptors with CXF Jaxws service.
This following link gives more detials of the CXF module in Mule and reference to Interceptors.
<cxf:jaxws-service .... ....>
<cxf:inInterceptors>
<spring:bean class="org.apache.cxf.interceptor.LoggingInInterceptor"/>
</cxf:inInterceptors>
<cxf:outInterceptors>
<spring:bean class="org.apache.cxf.interceptor.LoggingOutInterceptor"/>
</cxf:outInterceptors>
</cxf:jaxws-service>
Use Fault Interceptors to take control of the error processing.