My memory's a bit fuzzy, but I am pretty certain the "stun" reaction during pickpocketing came as a result of a suggestion from a player - I seem to remember when RS2 started, one of the changes made was that if you got caught picking a pocket, the NPC would attack you; you'd either kill it and have to find a replacement to keep thieving or you'd have to run away and come back. Anyone else remember that?