Cannot move or rotate child Object

I have an odd problem with Unity. I got a Swords Prefab and a Character with a sheath on the back. The sheath has a bone where the sword should be.

Now i parent the Instantiated Sword Object to the Sheath bone, which works just fine (i think?!). Now i have to Rotate the sword for 90degrees so that it fits perfectly in the sheath. But i cant change the rotation or position of the sword in the script. I`ve tried localPosition, position, rotation, localRotation, eulerAngles, localEulerAngles, nothing works. I can rotate the sword in the scene - view though. The sword model was imported from blender...is it important wich pivot i use there? Or could something different went wrong there?

Here is the important part of the script:

 public Transform Swords;
 public Transform rightSheath;
 
 void Awake () 
     {
 
         Transform swordR = (Transform)Instantiate(Swords, rightSheath.transform.position, rightSheath.transform.rotation);
         swordR.transform.parent = rightSheath;
         movement.direction = transform.TransformDirection (Vector3.forward);
         controller = GetComponent<CharacterController>();
         Spawn ();
     }