Makai Senki Disgaea 3/Power Leveling
You can do this only when you cleared the Ju-shinshi scenario. You get a neko-baba stick which steals items from enemies you killed(for a certain percentage which is about 20%).
When you get the stick equip "1" item you want to duplicate on a low level character. Go to that character's academy world. In the world you should see your character's fake there.Use the hero equiping the stick and kill the character's fake. If you're lucky you'll get the item you want with the same stats,innocence and sometimes better.
This requires also the same technique as the item duplication. First find equipment which adds EXP for you (keikenchi-tsuika-ya). You should be abe to find it if you go deep into item world.
Now duplicate the EXP+ equipment. Until the exp+ goes to 300.(this means EXP X3) Equip the item on the character. (this means EXP X9 if you have 3).
(Felt like adding the item duplication guide along as to explain the Power Leveling methode that goes along with it).
Kind Regards: Zetta