Maintenance for the week of October 5:
• [COMPLETE] ESO Store and Account System for maintenance – October 8, 8:00AM EDT (12:00 UTC) – 12:00PM EDT (16:00 UTC)
It goes against their design philosophy to alter already released assets. The only exception they make is if a texture is bugged or missing. They don’t add, remove, tweak or embellish already released items for aesthetic reasons.
Now you could argue that the mount missing special effects is a bug, but good luck with that.