One-Item Multi-Equipping & Unlimited Cash Glitch 
One-Item Multi-Equipping Glitch
Note: Works only on JPN version of "Ar Tonelico II" currently.

     This  glitch  allows  you to have one of any particular equipment
and be able to equip to all characters that can use it.

01) Make sure that chosen equipment is not equipped on anyone.
02) Go to the Items menu and to the Equipment section.
03) Choose that equipment you want to use for the glitch.
04) When you choose that equipment, it should open the party screen 
    menu.
05) Equip on all characters at that party screen 
    (assuming they can equip it).

     This  trick  will  put  that  equipment  amount into the negative
(since  it  is  not  possible  to equip that one equipment on multiple
characters).

Extra Notes:
     -  You  can't  use this glitch if member with that "equipment" is
not in your party (since you must un-equip before doing the glitch).
     -  This  glitch  doesn't work if you try to equip it normally via
the  Equip  Menu option, since it accurately keeps track the amount of
that equipment you have.


Unlimited Cash Glitch
Requirement: Must perform the "One-Item Multi-Equipping" glitch
Note: Works only on JPN version of "Ar Tonelico II" currently.
Credit to Dragnfly to first test and confirm the Unlimited Cash works.

     Sell that equipment (that was used for the "One-Item Multi-Equip"
glitch)  at  the  stores unlimited amount of times due to the negative
total count.