Got another one(taking this from the fantasitc line on Little Britain comedy)

I Think that when you atack a monster with a sword/axe etc it should make some noise esp and this alerts any enemies nearby..i.e hearing and sght which already is implemented in the game.

Now i think that for thieves stealth is necessery and so i say that certain weapons like daggers,short swords should have an attribute(which can only be used by theives) which would make them "silent" whlist attacking another monster..this would not alert any nearby monster in the hearing department.

Potion of shadows work in the sight depertment and i thnk a couple of these would be ideal for making(at least for thieves/assassin) players explore the stealth option.