A PC wields a 1-handed weapon one-handed. He wants to make a [disarm][1] attempt with his empty hand. The PC possesses the feat [Improved Disarm][2] but not the feat [Improved Unarmed Strike][3] or any other similar ability. 

I think that the PC provokes an attack of opportunity for making the disarm attempt unarmed. Put simply, I read disarm as an attack.

The PC's player claims that his PC does not provoke an attack of opportunity for three reasons:

1. A disarm is not an attack as such, but an attack-equivalent action, which he simply interprets as a standard action.
2. The Improved Disarm feat overrules the unarmed strike rules in this particular case.
3. The PC's considered armed because the PC's still wielding a melee weapon.

Who's right?


  [1]: http://dndsrd.net/specialAttacks.html#disarm
  [2]: http://dndsrd.net/featsAll.html#improved-disarm
  [3]: http://dndsrd.net/featsAll.html#improved-unarmed-strike