I have a level 85 Death Knight FW build in progress. I was a bit underwhelmed with it because of the latest update on conversion to phys now being affected by armor. I have the feeling that the very little Aether->Phys conversion the build proposes (only seal of might) was far from taking full advantage of Spectral Binding ; see my message here on this.
And btw, you provide a totally different answer in OP regarding conversion, than the one I’ve found on reddit. What you say in OP tells me I should really crave for converting as mush Aether as possible to Physical, because now those extra sources are all affected by armor, and so they need to be as big as possible to bypass it, hence 100% conversion highly wanted.