Controlling the update position of a cloned Gameobject C#

Hi everyone here's my problem!

I'm doing a 2D game were i got a ninja that slash when the mouse is press. The slash is a gameobject that get instantiated at the position of a empty gameObject everytime then die really quickly. Problem is when it get instantiated and if my player is moving the slash object is left behind.

What I want is that when the Clone of the slash is instantiated I want it's position to follow the slash GameObject position every frames. Anyones got an idea. Here's my code (it's in the mouseButton Event) :

 public class PLayerController : MonoBehaviour {
 
     public float MaxSpeed = 7f;
     public bool facingRigth = true;
 
     Animator anim;
 
     bool grounded = false;
     public Transform groundCheck;
     float groundRadius =0.2f;
     public LayerMask whatIsGround;
     public float jumpForce = 500;
 
     //Attacking
     public Transform slash;
     public GameObject slashObjectL;
     public GameObject slashObjectR;
 
     // Use this for initialization
     void Start () 
     {
         anim = GetComponent<Animator> ();
     }
     
     // Update is called once per frame
     void Update () 
     {
         //Jumping
         if(grounded && Input.GetKeyDown(KeyCode.Space))
         {
             anim.SetBool("Ground", false);
             rigidbody2D.AddForce(new Vector2(0,jumpForce));
         }
 
         if(Input.GetMouseButtonDown(0))
         {
             if(facingRigth)
             {
 
                 GameObject slashLCopy = (GameObject)Instantiate(slashObjectL, slash.position, slash.rotation);
                 slashLCopy.transform.position = new Vector2(slash.position.x, slash.position.y); //NOT WORKING!!!!!!!
 
             }
             if(!facingRigth)
             {
 
                 GameObject slashRCopy = (GameObject)Instantiate(slashObjectR, slash.position, slash.rotation);
                 //slashRCopy.transform = slash.position; //NOT WORKING EITHER!!!!
             }
 
 
         }
     }
 
     void FixedUpdate()
     {
         grounded = Physics2D.OverlapCircle(groundCheck.position,groundRadius, whatIsGround);
         anim.SetBool("Ground", grounded);
 
         //Jumping
         anim.SetFloat("vSpeed", rigidbody2D.velocity.y);
 
         float move = Input.GetAxis ("Horizontal");
         anim.SetFloat ("Speed", Mathf.Abs (move));
         rigidbody2D.velocity = new Vector2(move * MaxSpeed, rigidbody2D.velocity.y);
 
         if(move > 0 && !facingRigth)
             Flip();
         if(move < 0 && facingRigth)
             Flip();
 
     }
 
     void Flip()
     {
         facingRigth = !facingRigth;
         Vector3 theScale = transform.localScale;
         theScale.x *= -1;
         transform.localScale = theScale;
     }
 
 }