Forgive me if I make suggestions you've already tried.I see Amiel must have died between 1896 and 1900.The state of TX didn't require death records until 1903, but I understand some TX counties kept their own death records prior to that date.Now, they may not include names of parents, but worth a try.Also, obituaries, they sometimes come up with helpful little tidbits.His widow, on the 1900, census shows they have 8 children and she owns farm free and clear, so they might be considered "pillars" of the community and he could have a nice obit.(I see she's remarried by 1910.)
Have you tracked down when and where Amiel's brothers died?If later, they may have death certificates which do show full names of their parents.
Have you found when his mother Hannah remarried?She should show her maiden name on that marriage record, unfortunately sometimes on a second marriage a bride will give her previous married name, but again, worth a try.
Does ship's record show anything more then Saxony?Occasionally records will give more then actually required.