Disarm w/spiked chain

[Hypersmurf]

Sunder IS a feat.

Attack an object is the non-feat version.

Strike a Weapon, if we're getting technical.

As an attack, I'd think that it's perfectly possible as an AoO.

Table 8-4 disagrees with you.

Trip, Disarm, and Grapple have their own little "Action Type" section, and carry the double-dagger footnote symbol that states they can be used as an AoO.

Strike a Weapon falls in the "Standard Action" section, and lacks the double-dagger.

-Hyp.

 

[kreynolds]

Sunder IS a feat.

The sunder feat makes you better at striking weapons. That's it. You don't need the feat to strike a weapon. The point is that the action itself, striking a weapon, cannot be used as an AoO.

Attack an object is the non-feat version.

There is no "non-feat version". You have the action and you have the feat that improves upon the action. Sunder does not replace the action. It merely modifies it.

As an attack, I'd think that it's perfectly possible as an AoO.

Apparently not, but I wouldn't be surprised if this changed in 3.5. But then again, I wouldn't be surprised if it didn't either.