Axanthic is recessive, so it won't show up till it has both Axanthic genes from both sides. If I got a 100% het male, and a 100% het female and bred them, Would that produce a visible axanthic (if the BP gods smile upon me)
Yes, only if both het axanthics are from the same compatible line. I have NOT heard that any of the major lines were compatible. If someone is making that claim I'd want to see proof that one of the animals was not actually a double het.

The current accepted major lines of axanthics are

VPI - recessive
TSK - recessive
Jollif - recessive
Red Axanthic - Co-Dominant

And as far as I know, none of them have been proven to be compatible with each other.

I don't know much about the NERD axanthics so can't say anything about them.

There are other lines of wild caught axanthic that are being worked on. There are axanthic looking animals imported every year from Africa, many have not even been proven to be genetic much less compatible with other lines

Mark