2D dash/knockback?

So basicly what Im trying to do is a knockback effect for my 2D fighting game, however I only seem to be able to make the knockedback player teleport back instead of being smoothly pushed back. Any help?

 using UnityEngine;
 using System.Collections;
 
 public class playerFighting : MonoBehaviour {
     public int health = 1000;
 
     public float initialDelay;
     public float afterDelay;
     public float attackDelay;
     public float shurikenSpeed;
 
     public bool isAttacking = false;
     public bool inRange = false;
     public bool isHit = false;
 
     public int attackStacks = 0;
 
     playerMovement pm;
     gameManager gm;
 
     GameObject target;
 
     new string name;
 
     bool shurikenDelay = false;
 
     Animator anim;
 
     // Use this for initialization
     void Start () {
         name = this.gameObject.name;
         anim = GetComponent<Animator> ();
         pm = GetComponent<playerMovement> ();
 
     }
     
     // Update is called once per frame
     void Update () {
         //Attack
         if (Input.GetAxis (name + " Attack") == 1 && !isAttacking && pm.jumpEnable > 0) {
             StartCoroutine(Attack());
         }
 
         //Shuriken
         if((Input.GetAxis(name + " ShurikenX") >= 0.5 || Input.GetAxis(name + " ShurikenY") >= 0.5 || Input.GetAxis(name + " ShurikenX") <= -0.5 || Input.GetAxis(name + " ShurikenY") <= -0.5) && !shurikenDelay){
             StartCoroutine(Shuriken());
         }
 
         //Health
         if (health <= 0) {
             Debug.Log (name + " lost. Game Over!");
             gm.GameOver();
         }
 
         anim.SetFloat("Attack", Input.GetAxis(name + " Attack"));
         anim.SetInteger ("AttackStacks", attackStacks);
         anim.SetBool ("isHit", isHit);
     }
 
 
     IEnumerator Attack(){
         attackStacks = 0;
 
         isAttacking = true;
         yield return new WaitForSeconds (initialDelay);
         //Debug.Log (name + " is attacking.");
         if (inRange) {
             while(Input.GetAxis(name + " Attack") == 1){
                 float timer = Time.time;
                 float reset = timer + 1;
 
                 if(attackStacks < 2){
                     target.GetComponent<playerFighting>().isHit = true;
                     target.GetComponent<playerFighting> ().health -= 10;
                     yield return new WaitForSeconds (attackDelay);
                     attackStacks++;
                     target.GetComponent<playerFighting>().isHit = false;
                     yield return new WaitForSeconds (initialDelay);
                     continue;
                 }
 
                 else if(attackStacks == 2){
                     if(target !=null){
                         Debug.Log("Power attack!");
                         target.GetComponent<playerFighting> ().health -= 20;
                         target.rigidbody2D.AddForce(new Vector2(-this.transform.localScale.x * 10000, 1) * 100 * Time.deltaTime * 0.5f);
                     }
                     //powerAttack
                     break;
                 }
 
                 timer += 1 * Time.deltaTime;
 
                 if(timer == reset){
                     attackStacks = 0;
                     break;
                 }
             }
             if(target != null)
                 target.GetComponent<playerFighting>().isHit = false;
         }
         if(target != null)
             target.GetComponent<playerFighting>().isHit = false;
         yield return new WaitForSeconds (afterDelay);
         attackStacks = 0;
         isAttacking = false;
     }
 
     IEnumerator Shuriken(){
         shurikenDelay = true;
         GameObject Shuriken = (GameObject)Instantiate(Resources.Load ("Shuriken"));
         Shuriken.GetComponent<shuriken>().Player = this.gameObject;
         Shuriken.GetComponent<shuriken>().player = this.rigidbody2D;
         Shuriken.transform.position = new Vector2(this.transform.position.x, this.transform.position.y + 0.1f);
         //shuriken = Shuriken;
         Shuriken.rigidbody2D.AddForce(new Vector2(Input.GetAxis(name + " ShurikenX"), Input.GetAxis(name + " ShurikenY")) * shurikenSpeed);
         yield return new WaitForSeconds (1.5f);
         shurikenDelay = false;
     }
 
     void OnTriggerEnter2D(Collider2D other){
         if (other.tag == "Player") {
             Debug.Log("In range");
             target = other.gameObject;
             inRange = true;
         }
     }
 
     void OnTriggerExit2D(Collider2D other){
         if (other.tag == "Player") {
             Debug.Log("out of range");
             target = null;
             inRange = false;
         }
     }
 }