Having made "Fling" one of my signature spells, a question has come up in our regular group as to the effects of throwing weapons. Namely, how would you go about parrying or catching a thrown weapon or object?

Similarly, how would you deal with items being "Fling"ed, such as held weapons or objects in pockets/holsters (but still visible). Are the holders or owners allowed tests? Can you counterspell for something being "fling"ed from your hands when it's not cast on yourself but on the item?

You can counterspell the spell as it is cast. Steet Magic has two throwing-related adept abilities. One allows you to throw anything (ie, pens, mugs, playing cards) and another allows you to parry/catch thrown weapons.

There was a third ed adept power that let you grab thrown items. It seemed like a waste of points but it more than made up for it in humor value when you finally had the chance to catch and return every single hand grenade the opposition threw at you.

It's in Street Magic and I wouldn't go about catching hand grenades ...

Missile Parry.

I think fling specifically mentions some kind of strength test if you're trying to fling something out of someones hand.
As far as counterspelling, if its on the person (thusly inside their aura) I'd allow counterspelling against the spell as long as the person was being counterspelled.

First thing we checked, that and manipulation spells. No strength test, but it does give a strength to the throw.

I'd use the strength check from levitate for trying to fling something out of someones hand.