I've read two things now that I can remember that used the term "Wagnerian Overtones". Now, being me I immediately think Wagner, and the harmonic overtone series.

Both times, they've been used to describe things not musical. I think it read something like: Revolution with Wagnerian Overtones. Does this even have anything to do with music? thx in advance smarties.
Inflatable Guitar
Digitech GSP 2101/Mosvalve 962/Yamaha S412V
My Imagination
I doubt that its referring to the harmonic overtone series, but rather, harmonic or motivic aspects that resemble Wagner's works.

Wagner is now a synonym for "grandios, overly dramatic, highly emotive".

Is that what you're looking for?