This has been already discussed here but actually I can find only https://developer.jboss.org/thread/236804. As I wrote:
"Weld is scanning your archive (Processing weld deployment ViViFYdServer.war), which seems to cause the problem. You can try to set require-bean-descriptor to true in weld subsystem in your standalone configuration. Seam apps should be deployable on WildFly"
but it's useful to read the entire thread discussion.
It worked. Thanks a lot.