The gear doesn't have "#forge:weapons" or "#forge:armor" in the NBT tags, which I am assuming is why apotheosis affixes cannot be applied to them. Pic below is a pike from Spartan Weaponry, which works fine with affixes.

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I have added the tags. I have not tested Spartan Weaponry. When the new beta version releases, let me know with a new issue if it doesn't work yet.

Will add them. Did not know this was a thing :O

A quick addendum; the armor seems to work with the affixes, and I am not sure if armor requires any tags in general, as I don't see armor with an equivalent of a "forge:weapons" tag. Either way hoping this ends up being a simple fix, and is indeed only an issue with those tags.