Doesn't this seem like a bug? I like riding horses, mostly for the role playing aspect, but the problem is when I dismount my horse to engage an enemy:

My horse aggressively charges enemies with a braveheart-like passion. OR sometimes my horse won't rush into battle, but enemies will attack my horse first and ignore me. So then my horse dies if I can't kill the enemy first.

This would make perfect sense if my horse was riding me into battle, but that isn't the case. hey there's a mod idea.

-Bonus bug is when I went back to the stable near solitude to buy the same one again, the shopkeeper will take my money but there will be no horse to to take.

Enemies did this in Oblivion as well. Not really a bug, just the way the AI is coded.

Those are some smart bandits. Turn back on knight in full enchanted daedric armor with flaming warhammer to attack horse. Logical!

If this is just the way that horses have been scripted since Oblivion, then that is just some really really poor and shameful coding. It may not be a "bug" in the technical sense, but it is definitely something needing fixing.

Personally, this has helped me ALOT. But then again I do use Shadowmare as a tank for when I fast travel into areas that's surrounded by enemies. I sometimes hide behind my horse and snipe the enemies out with my bow.
God I'm abusive to Shadowmare...

It justa kind of [censored]s up my immersion and makes me want to punch my ps3 when it happens. That is why I am horse-free right now. I prefer to pretend that horses are not semi-divine beings that can eat 800 pts of steel and regenerate like a troll. Until (unless) a patch comes out to make them stop acting like Chuck Noris all the time, I'm just going to pretend that part of the game doesn't exist.
Same goes for most companions.

Lol shawdowmare is a chuck norris equal

Your horse Is loyal. End of story.

I've accidentally killed a few of my horses by them getting in my way from attacking the enemy first. This is probably the reason why there was a horse armor addon for Oblivion.