Danke fürs drüber schaun.
Ganz unten, letzte def:

Code:
class Scene_waffen
  def main
    @actor= $game_party.actors[0]
    $data_weapons[@actor.weapon_id]
    @data= []
    @icon_name = []
    @name= []
    @description=[]
    
   get_equip
      @status = Window_status_ausrüstung.new(@actor)
    #  @status.active=false
    @command_window = Window_Ring_Command.new(1,$game_player.screen_x-30, $game_player.screen_y-50, @icon_name, 60)
    @beschreibung_window = Window_beschreibung.new(@name,@description)
    @beschreibung_window.z = 400
    @spriteset = Spriteset_Map.new
    # Main loop
    Graphics.transition
    loop do
      # Update game screen
      Graphics.update
      # Update input information
      Input.update
      # Frame update
      update
      # Abort loop if screen is changed
      if $scene != self
        break
      end
    end
        Graphics.freeze
    # Dispose of command window
    @command_window.dispose
    @beschreibung_window.dispose
    @spriteset.dispose
    @status.dispose
   
  end
  def update
    @command_window.update
    @beschreibung_window.update
  if Input.trigger?(Input::B)
      # Play cancel SE
      $game_system.se_play($data_system.cancel_se)
      # Switch to map screen
      $scene = Scene_Map.new 
      return
    end
ausrüsten(0)
if Input.repeat?(Input::	LEFT )
  @command_window.move_left
    $game_system.se_play($data_system.cursor_se)
unless @command_window.index == 0
    equip
    end
    
  end
  if @command_window.index == 0
    @status.set_new_parameters(nil, nil, nil)
    end
if Input.repeat?(Input::RIGHT)
 @command_window.move_right
    $game_system.se_play($data_system.cursor_se)
   unless @command_window.index == 0
    equip
    end
  end
  if Input.trigger? (Input::UP)
  $scene = Scene_ausrüstung_body.new
end
if Input.trigger? (Input::DOWN)
      $scene = Scene_Menu.new
  end
 #       case Input.dir4
#  when 4 then @command_window.move_left
 #   $game_system.se_play($data_system.cancel_se)
 # when 6 then @command_window.move_right
 #   $game_system.se_play($data_system.cancel_se)

#end
#@index = 0
#while @command_window.index != @index and @command_window.index !=0
 # @index= @command_window.index
end    
 def equip
   item1=@data[0]
    item2 = @data[@command_window.index]
      @actor.equip(0, @data[@command_window.index].id)
      # Get parameters for after equipment change
      new_atk = @actor.atk
      new_pdef = @actor.pdef
      new_mdef = @actor.mdef
      # Return equipment
      if @data[0] == "nix"
        @actor.equip(2,0)
      else
      @actor.equip(2,item1.id)
      
      end
      # Draw in left window
      @status.set_new_parameters(new_atk, new_pdef, new_mdef)
    #@item1=$data_weapons[@actor.weapon_id]
    #
      #@actor.equip(0, @data[@command_window.index].id)
     
#    end
      
    end 
    def update_icons
      @data.clear
    @icon_name.clear    
    @name.clear
    @description.clear
    get_equip
    @command_window.update_icons(@icon_name) 
    end
    def get_equip
      if $data_weapons[@actor.weapon_id] == nil
        @data.push("nix")
    @icon_name.push("nix")
    @name.push("")
    @description.push("")
    else
    @data.push($data_weapons[@actor.weapon_id])
    @icon_name.push($data_weapons[@actor.weapon_id].icon_name)
    @name.push($data_weapons[@actor.weapon_id].name)
    @description.push($data_weapons[@actor.weapon_id].description)
    end
    weapon_set = $data_classes[@actor.class_id].weapon_set 
    for i in 1...$data_weapons.size
        if $game_party.weapon_number(i) > 0 and weapon_set.include?(i) and $data_weapons[i] != $data_weapons[@actor.weapon_id] 
          @data.push($data_weapons[i])
          @icon_name.push($data_weapons[i].icon_name)
          @name.push($data_weapons[i].name)
          @description.push($data_weapons[i].description)     
        end
      end

      
  
    end
    def ausrüsten(type)
      if Input.trigger?(Input::C)
        $MSS.change_weapon(1)
        $game_system.se_play($data_system.equip_se)
        @actor.equip(type, @data[@command_window.index].id)
      update_icons
      @status.refresh
    end
    end
  end
Im Endeffekt möchte ich abhängig von der ausgerüsteten Waffe $MSS.change_weapon(ausgerüstete Waffe) aufrufen.
Ginge also auch über ein Common Event, nicht nur über dieses Menü.