I havent used PP in a SD situation but I have used it when play fighting with my friends.
There is a tradition in Greece that on the first night of halloween (it lasts a week in Greece) everyone goes to the centre of town and beats each other with foam baseball bats
If you hit someone's bicep with a phoenix eye (where the middle finger in a normal punch is slightly protruding) their hand opens and releases whatever they are holding.

Does that count?

Pericardium #2? Middle of bicep? The stun is probably what makes them let go.

Pericardium?
Isnt that that fibre that surrounds the heart?
I dont think its from the stun, although I recently tried to do it softly on someone and it didnt work, so you might be right.
I also used a PP on that kid who tried to slap me and I grabbed him by the throat, that was fun!

There are places to strike on the arm in a manner that will make their hand physically open or release.
I have beens shown these,had them done to me,and done them to other people,even when they are resisting.They are moves that are 'hidden' in many kata.

[derailment]
I've been shown the technique to make someone's hand open and performed it on myself- by accident. Playing around I went to hit my girlfriend on the leg and ended up hitting with the inside of my forearm. My hand went instantly numb and I couldn't use it for a couple of minutes. Really freaky...
[/derailment]

There's quite a few good points on the arm that hurt like hell. If you're interested in the point location there's a really good database here