I should check my email before we go writing this in digital stone, but I feel like I recall Lazlo saying Saxon was a sport from mettenianum, so reversions would theoretically be s. mettenianum. Another issue with this is that "mettenianum" itself is a name which comes with some doubt attached, Mountain Crest Gardens sells a beautiful plant under that name which appears to be a wulfenii x tectorum but I know our database has the mettenianum label synonymous with tectorum which would indicate it to be a scientific name that could blanket any tectorum cultivar or species collection. I suppose if that's the case mettenianum doesn't really mean much and one could argue that using it to describe the Mountain Crest plant would infact be appropriate. Another possibility is that I am incorrect about the Mountain Crest plant having any wulfenii blood and that it is in fact a pure tectorum collection, distinct from other tectorums and should be titled as s. tectorum var. mettenianum, in that case 'Saxon' couldn't be a variegated version of the "variety mettenianum" because your reversions don't resemble the Mt. Crest offering which is a sort of soft purple color somewhat similar to 'Magnificum'.
So there's a very educated way to say "I don't know"