So I'm playing a cutpurse rogue and I go to mug a wizard he is wearing an amulet and some rings and a pouch on his side. Can i go for the amulet or rings instead of his obviously magic component pouch?
Sure, why not? Likely jewellery is a lot easier to fence anyway.
If you're up against a boss and you successfully sneak behind him when he has one of his weapons sheaved, I find it annoying that you can't just steal the weapon, because from what I read, you can only steal whatever's classed as a small object and I'm pretty sure a rapier or Katana is bigger than a small object.
It makes sense to be able to do it and then just use their spare weapon against them.