The presence of SLF4J-simple within the Weld SE jar causes problems for those wanting to use a different SLF4J provider (eg: jdk14).
This comment from Ceki points to a good solution, using SLF4J 1.6:
Ceki Gulcu - 23/Apr/10 04:17 AM
As of SLF4J version 1.6.0, if no binding is found on the class path, then slf4j-api will default to a no-operation implementation discarding all log requests. Thus, instead of throwing an exception, SLF4J will emit a single warning message about the absence of a binding and proceed to discard all log requests without further protest. If Weld's distribution includes slf4j-api.jar but no binding, then even in the absence of any SLF4J binding on the class path, Weld's distribution will still work out-of-the-box, and without requiring the end-user to download a binding from SLF4J's web-site. Only when the end-user wishes to enable logging will she need to install a binding.
The problem with this currently is that version 1.6 is still alpha, so resolution of this issue will have to wait until version 1.6 is released as stable, and becomes available in the JBoss maven repositories: