First Person Melee System - How to attach a weapon which swings and hits an enemy?

Yes, it sounds like you are thinking along the right lines.

Keep a reference(s) to your weapon prefab(s) in your script. Then, when the weapon is first equipped, you can create an instance of your weapon prefab, and set its parent to your character object, using code something like this:

public Transform[] weapons; // array of available weapons private Transform currentWeapon; private selectedWeaponIndex = 0;

 // your other movement/weapon select/general game code here...

 if (attacking) {
     if (currentWeapon == null)           
         Equip(weapons[selectedWeaponIndex]);
     }
     selectedWeapon.animation.Play();
 }

 // instantiate weapon at character position:
 Transform weapon = (Transform) Instantiate(weaponPrefab, transform.position, transform.rotation);

 // attach weapon to character:
 weapon.parent = transform;

The above example is illustrative only, and assumes there's an array of available weapon prefabs. It also does not include all your other code for moving, selecting weapons, etc, so you'll need some basic general Unity scripting knowledge to get it set up correctly.

As illustrated above, if your weapon prefab itself has an imported bones-based animation attached to it, you can play the animation using the Animation scripting commands, such as Animation.Play.

If you don't have a bones-based animation created outside Unity for each weapon, there are a few alternatives to this technique.

One would be to have a single generic imported bones-based animation set up on your character which could be used for all weapons (such as a generic "swinging arm" animation), and you could then instantiate any suitable weapon (such as a sword, axe, club) at the position of the hand, and parent it to the "hand bone" of the animation, so that it follows the animated movement of the hand.

Alternatively, you could Unity's built in Animation Editor to define an animation for each weapon within Unity. These animation clips can then be used in a similar manner to that described above for imported bones-based animation.

Once you have all this in place, you need to move on to the problem of detecting hits and inflicting damage.

You may want to do this based on a simple Radius approach (i.e. if you attack within a certain radius, you incur a hit on the enemy). You can do this by simply checking the distance between the two characters using code something like this:

if ((enemy.transform.position - transform.position).magnitude < 2) {
    enemy.InflictDamage(1);
}

The above assumes that "enemy" is a reference to a script on your enemy character, and that script has an "InflictDamage" function. It inflicts 1 point of damage, if the player is within 2 units of the enemy.

If the player has the ability to turn around and face any direction, you'd probably also want to check whether they're facing the correct direction (eg, not attacking with their back to the enemy!). Something like:

Vector3 enemyDelta = (enemy.transform.position - transform.position); if ( Vector3.Angle( transform.forward, enemyDelta ) < 45 ) { // we are facing the right way!

 if ((enemy.transform.position - transform.position).magnitude < 2) {
     enemy.InflictDamage(1);
 }

A completely different method would be to use colliders with Unity's physics system, to detect whether the weapon actually passes through the enemy's collider. To implement this, you'd need to set up a trigger collider on the weapon object, and make sure your characters have a collider & rigidbody component. You could then use the OnTriggerEnter function on your enemy scripts to detect if the player's weapon actually came into contact, and incur damage from within that function.

Hope this helps get you started.