bozia2012
Arcane
Dexterity (like any other "big stat") give you a bit more than +% bonuses. Dexterity from what I remember (I'm about 9 km from my pc) gives you for example ability to fight unarmed. Intelligence tree can give you the ablility to gather alchemical components (for this you'll also need proper knowledge). Dunno about thieving skills - this was unsignificant in the books (or not?) so I figure it didn't make to the game.