The Sundering Rhino's Charge is one of the seven bonus items in the '06 version
of the European Guild Wars and the American game of the year edition.
It is automatically customized when acquired, and cannot be dropped or traded from one's inventory. Nor can it be salvaged. It can be deleted to make space, however.
You can add a hammer grip to this item.
To acquire this item, once you have either the game of the year/1 million seller edition of Guild Wars or have purchased their availability from the Guild Wars Shop, type /bonus to get all of the special weapons, which are unlocked on your account, spawned into your inventory.