While showing around my deed to a friend today,he got attacked by one of my hell horses hitched to my cart,and my friend unintentionally was able to harm the horse even though both hell horses are branded and hitched,and on a pve server.Now, normally another player it is not able to attack back a branded and hitched horse,but what i found after getting some info is that if the hell horse is making a bad move can be attacked back, in this specific situation,due to an error in the way it was coded.
[13:15:32] The adolescent Eaglehunting kicks R... pretty hard in the chest and irritates it.
[13:21:38] R...cuts the adolescent Eaglehunting very hard in the stomach and harms it.
Hopefully this issue can be solved.
Thanks to DrSatan for trying to help.