From the D&D
On a normal disarm attempt, you and the target make opposed checks using a melee attack. But what if you're trying to knock a wand out of a wizard's hand? Would the wizard make a roll using only his Dexterity modifier?
Use opposed attack rolls for any disarm attempts (the better you are at combat, the harder it is to take things away from you).
If the target of the disarm is not a weapon, and the target is something that the defender has in hand or carries on a belt or other fairly accessible place, the attacker makes an attack roll against the item first. (A normal disarm attempt against a weapon doesn't require an initial attack roll, but that is because the weapon is assumed to be in use and pretty easy to strike.) Use the rules for attacking inanimate objects on page 135 of the Player's Handbook. The item's Armor Class depends on its size, as shown on Table 8:11; remember that a held, worn, or carried object uses the wielder's Dexterity modifier to Armor Class (instead of its own -5 penalty) and gains the benefit of any deflection bonus to Armor Class that the wielder has.
If the initial attack strikes the object, make an opposed attack roll to see if the defender drops the item.