The Sorcerer class follows a very natural path of progression from the mage archetype. Rather than being saddled with the same old spells and a spiffy new pet like the Spiritmaster, you can now focus all of your efforts into bending the weave of the universe to your will. The destruction you were able to wreak as a mere mortal mage doesn't remotely compare to the hell you'll learn to unleash upon your foes as an immortal Sorcerer. Once the excitement of your recent ascension wears off, you'll quickly begin to realize that you're a lot like a glorified Mage at this stage of your development. While you may not get a lot of new spells, you have grown in power, so don't get too depressed. The treasures are just around the corner.

Given all of the information available to you in the description of both, it looks like the Orb of Karma is best to choose from starter weapons. The Orb does more damage, has better stats (minus the Magical Accuracy), and let's face facts; everyone likes to play with something new. Sounds great, right? Guess what though. You should take the Spellbook of Karma instead. There's just one disturbing little fact the description of both items fails to mention. The Orb is a close range (as in melee distance) weapon. This works perfectly for a Spiritmaster, but for the Sorcerer, it's a near-deadly mistake. The Spellbook is a ranged weapon, just like you've been using all along, so choose wisely.