Like the title says this bug occurs everytime after Eivor rides a horse. This bug happens only if you have a long weapon like a spear in Eivor's left hand and short weapon like an axe in Eivor's right hand. After horse riding and taking out the weapons the spear in the left hand will be upside down and Eivor will not place it on his shoulder when walking like he's supposed to do. I also discovered that saving and reloading solves the issue but I can't do this everytime Eivor rides a horse.