All these years , since 2004, I see that the horse max level is 30 but we can only level it up to 21. I know this isn't a very exciting idea but it would be nice if the horse could get to 30lvl.
Suggest getting a different new shape and a new designed cosmetic as an armour (maybe different colour when you are the boss of a guild) and of course making the defense and speed a little bit better.
In addition, we could use some different horse medals that will be more difficult to drop and more expensive. Also the cool-down until the next quest should be a day or more. The feeding of the horse won't change.
I don't know if this is possible because it will require many changes in the game's files but I'm sure the developers when they wrote "max level 30" had some ideas in their heads that never came out.
Let me know what you think about this.