Nope, but even if you managed to steal Frostbrand I'm sure that mage would still show up to take it back, so in the end what's the point other than to say, "Hey, I pick pocketed Drizzt!! How cool me!" Oh wait, that does sound like fun to be able to say...
In BG1 I managed to pickpocket Drizzt during his fight against some monster (gnoll or something) just to see what happens. It took more than 20 tries, but I managed to get both his sword and drizzt just continued fighting with two swords !
BTW, since he never reminded me to give him the swords back, my fighter took care of them
In my first run, I used a swashbukler/mage. I did pickpocketed Drizzt and they're all trash. You either get coins/gems (cheap), and wooden stakes. I believe it's impossible to steal something that's being equiped. I tried pickpocket Aran for elven chain but all I got were some cheap gems and coins.
Hehe, I just let Bodhi work on him for awhile and picked up his eq... Defender +5, another scimitar (Frostbrand IIRC) and Mithril Chain +4 I believe. Tho the blasted mage took the goodies when I left the crypt
But don't forget, a master theif can always steal or rob the weapons out of their hands. Probably not pickpocket, it's more like a parry, arm lock or whatever the proper name is for that skill.
Disarm a opponent IS a accepted move. already covered in AD&D 2nd Edition, it required a senseful hit in order to do that(and NEVERWINTER is based on 3rd edition anyway).
Besides a opponent is hostile towards you we are talking about stealing something that someone is holding in their hands.
I hope that in Neverwinter after being disarmed, the opponent remembers to pickup its weapon from the floor.
I did pickpocket him in the crypt. And I was a 14 level thief or something. But all I got from him was a lousy something I don't even remember, I guess some gold or gems. But no scimitar... When I tried the second time I got "Target has no items." Bummer.