Ebony is incredibly close grained and it is naturally moisture resistant, so it does not take much to set it up - I only use Ren Wax and have never had a problem.

I have tried hardening-type oil finishes like tung on very dense hardwoods before, but they don't seem to work that well - not enough penetration I suppose, and tend to buff off. Maybe I just didn't expreriment enough though.

Regards,
Neil