Targeting Script

You could have a basic class which contains the player's stats. like,, hp,mana,class(warrior,etc),etc. class this BaseChar script.

Create your multiple objects which could be multiple players. Something like..

 player1 = BaseChar()
 player2 = BaseChar()

then, you could use a Ray to check collision. Create a ray when mouse button is pressed. Have this ray 'point' out to into the game world which will make an invidsble line and have another script check for collision. Then when a collision has occurred.

 OnCollisionEnter( object : Collider ){
    object.GetComponent(BaseChar)   // <-- this gives you the character stats

    // so say you have a function to display all the properties of the class like..
    object.GetComponent(BaseChar).printAll() // which could print every variable you want
 }

You will need to use Raycasting to check when the collision hits some object http://docs.unity3d.com/Documentation/ScriptReference/RaycastHit-distance.html

I am not 100% sure on the exact code needed. You will need to look up Ray and RaycastHit.

@cdrandin's answer does answer your questions, but he is also showing you a good way of structuring the data and routines assiciated with a specific character. Here is a simpler example (done in C# sorry): Make a script that is empty for single global variable called type.

 public class CharacterType : MonoBehaviour
 {
     public int type = 0;
 }

In Javascript I think you can do this in a single line like "var type : int = 0;" Attach this script to all your character objects. Set the value of type in the inspector to different values for different character types: 0 - Mage, 1 - Warrior, 2 - Archer, etc;

Now to get that data from a collision you do something like this (C# again)

 RaycastHit hit;
 if (Physics.Raycast(ray, out hit))
 {
     CharacterType ct = hit.collider.gameObject.GetComponent<CharacterType>();
     if (ct != null)
         Debug.Log ("Character Type = "+ct.type);
 }

Using the RaycastHit and GetComponent(), you can get access to any script attached to the game object, and the information about your character can be stored with the object.

HI,You can do it two ways one is by creating an enum other by using tags.if you want to use tag Here is the script By the way what is "out hit"i didn't see you declare it any where and dont use && hit.transform.CompareTag("Hero")) after Physics.Raycast because if you do so it only casts a ray only when its an object tagged("Hero").Since there is no raycasting it cant check wether it has hit an object with tag(Hero) or not The ray shooting script(Alter these in your script)

 Transform selectedTarget;
 
 
 void Update(){
     if (Input.GetMouseButtonUp(1)){ // when button clicked...
           RaycastHit hit; // cast a ray from mouse pointer:
           Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
           // if enemy hit...
               if (Physics.Raycast(ray,hit,10000)){
     if(hit.collider.tag == "Hero"){
     DeselectTarget(); // deselect previous target (if any)...
                  selectedTarget = hit.transform; // set the new one...
     
        SelectTarget(selectedTarget); // and select it
     }
         }
       }
     }
     function SelectTarget(Transform obj){
     obj.GetComponent<Hero_Script>().selected = true;/////you can replace Hero_Script with your script name
     }
     Transform[] Army;///Add your hero and all other AI to this array
     
     DeselectTarget(){
     foreach(int obj =0;obj< Army.Length;obj++){
     if(Army[obj]!= selectedTarget){
     Army[obj].GetComponent<Your AI Script name>().selected = false;
     }
     }
     }

Now just add this to your Hero or Mage script

 bool selected;
 
 //your other code
 void Update(){
 if(bool){
 ///your code goes here
 
 }else{
 ///your code to make the Ai go to idle animation 
 }
 }