I'm sorry to say that Knock is not good here, it's one of those particularly cheeky type chests which is warded against simple spells.
You can rob the Duchel Palace without losing any reputation or attracting any nasty attention for the undesirables if you use that rather dandy magic cloak thing from the fat guy in Beregost to charm the Flaming Fist chappies before you go a-theiving. And as far as I'm concerned, if I dont stand to lose anything though some dirty business, there aint no moral dilemma
