I love this mod, it's awesome!
But, The drops from your unique horses seem to have little to no use outside of the oracle. They don't stack, making them very inventory intensive, and they have no value to vanilla play. Meaning they just start to stack up after a while with some play styles.
My suggestions: make them marginally stackable, maybe 16-32, and give each item a crafting grid breakdown.
Insert horse part, gain x resource.
For example, Destrier hide can be turned into 2 leather, Pegasus feathers be turned into 2 standard feathers, Nightmare hooves into blaze powder, and Unicorn horns into sand. (cause if you grind it up, you lose all the magic.) Kirin have antlers, if they drop those, let them be turned into 4 sticks per pair. (antlers make great tool handles) Hippocamps have scales, if they drop those, let them be turned into bonemeal. (fish scrapings make good fertilizer)
This would get rid of clutter and allow for them to have use outside of your mod, vanilla use and other mods as well, extending the reach of the resource without devaluing the source.