Why does my List overwrite itself when using .Add?

So I'm working on a GameDatabase editor for my project. I've created a custom asset from a ScriptableObject and a Weapon class that extends System.Object. The goal is simple: I want an editor window I set the data for the new weapon in and hit the add button and it will populate a weapon var in the editor window and assigning that to the database asset using .Add.

The problem is: When I use .Add and pass the newly set weapon it overwrites all previous weapons in the asset's weapon list. Does anyone have any idea why? I can't for the life of me figure this out.

EDIT I updated the script below to reflect the proper way to use .add with a list to add items via the editor window.

The Editor Window:

  class GameDatabase extends EditorWindow {
         
     //Weapon Variables
     var wepname : String = "Weapon Name";
     var description : String;
     
     //Database
     var database : DatabaseClass;
     
     //Create Window
     @MenuItem("Window/GameDatabase")
     static function Init () {
         var window:GameDatabase = EditorWindow.GetWindow(GameDatabase);
         window.Show();
 
     }
     
     function OnInspectorUpdate () {
         database = Resources.Load("database");
     }
     
     function OnGUI () {
         
         //Weapon Properties
         GUILayout.Label ("Weapons", EditorStyles.boldLabel);
         wepname = EditorGUILayout.TextField ("Name", wepname);
         description = EditorGUILayout.TextField ("Description", description);
             
         //Button to Generate Weapon Data for Database
         if (GUILayout.Button ("Add Weapon to Database")) {
             var newWeapon = new Weapon();
             weapon.name = wepname;
             weapon.description = description;
     
             database.weapons.Add(weapon);
     
             EditorUtility.SetDirty(database);
         }
     }
 }