I run a combination sorcery/finesse character, so I'll share my experiences.
Chakrams are definitely an excellent ranged weapon, so make sure you take the abilities that give you bonus to chakram damage and unlock their charge attacks. Charging takes time, but can severely damage or thin out weak enemies from the fight. Even uncharged, they can hit several enemies in a wide swath in front of you, so they're my go-to weapons in most situations.
You can pair chakrams with a dagger or faeblade if you want to sneak, but I think this is only really viable after you have the smoke bomb ability. Up to that point, I'd recommend taking whatever secondary gives you the best passive bonuses. Chakrams are good up close and from a distance, so a second weapon is pretty overkill, honestly.
Sorcery Offensive Abilities
As far as offensive abilities go, I like Storm Bolt and Ice Barrage. Storm Bolt gives decent damage, but it's slow to recharge. At higher levels and with its support abilities, you can sometimes stun. Ice Barrage is a more rapid-fire attack, which has the bonus side effect of raising your Fate meter quickly. Casting either of these spells back-to-back with shadow flare gives you a pretty strong 1-2 magic punch against most enemy classes.
Sorcery Support Abilities
Healing Surge is worth points as a support spell, since can give you back lost life. However, it's only really good in situations where you're not under fire (ie, between enemy encounters). You have to stand still and hold the button down in order to get its full effects. I haven't yet used Sphere of Protection, since my character isn't as "squishy" as a full-on mage, so I don't really require the additional defense.
Abilities To Ignore
I've played with the Sorcery summon, (Faer Gorta) and I can't say that I'm impressed. It's a bit slow to move and attack, and doesn't do much damage compared to my weapons and spells. If you're expecting it to tank, it doesn't. I have a level or two into Mark of Flame as well, but I find that the extra effort of doing the mark, and then holding the button to detonate is a bit failure prone. There's a bonus to fire damage skill above Mark of Flame that you might want - many Chakrams have bonus fire/burn damage, so boosting that is worth the 1-point investment in Mark of Flame.
I never use a scepter or staff, so I completely ignored those skills. However, you'll have to put a point into Arcane Weaponry 2 (which has no chakram benefit) in order to unlock 3/4 (which do). The dodge move with the Chakrams is completely overpowered, and tends to stun as well as hit several times. It works great against enemy mages that tend to protect themselves with anti-magic fields, and have an annoying tendency to teleport.
I assume that since you're coming from a finesse build, you already have a pretty clear idea about what finesse abilities work for you, but I'll give a quick rundown anyhow:
- Daggers/Faeblades - Invest points if you plan on using a dagger or faeblade secondary.
- Assassin's Art/Smoke Bombs - if you're going to be using a dagger or faeblade secondary, invest in this to get better results from stealth hits.
- Envenomed Edge - Works with chakrams, so max this one out.
- Frost Trap - I don't really see much of a use for this besides getting the related achievement...
- Shadow Flare - worth the investment in points because it fires fast, knocks back, and the second hit does decent damage.
- Longbows - Chakrams > Longbows.
- Lunge - Not especially interesting, given the "Poison Blink" ability you'll gain from your Finesse/Sorcery destiny card. With Poison Blink/Lunge, you can teleport through and do damage to your enemies.
Note also that you can roll/blink while you're sneaking and you won't increase your chances of detection. This might be non-obvious, since the "blink" is quite noisy. While smoke bomb'ed, I've even poison blinked through enemies and done damage to them without them detecting me.
I use a combination of finesse equipment and sorcery equipment on my character. Sorcery equipment sacrifices defense for increased mana regen time in most cases. I typically wear a finesse class body armor piece, and at least one other finesse piece (depending on what I have available). The other minor armor pieces I'll use sorcery gear on. This way, I get the benefit of the high mana regen rate without sacrificing too much armor-wise.
Crafting your own armor with Blacksmithing is also a solid plan, since you can balance your armor set the way you want. My armor gives me massive Mana boosts, plus with sagecrafting I can make +2 mana regen/sec gems, which mean that I can cast throughout the entire fight without ever running low.
As I played on the Xbox 360, I only had access to 4 abilities at any given time. I would leave the "active" abilities on, and then take them off my active ability list (they persist even when they're not mapped to buttons). Then I generally had Ice Barrage or Storm Bolt, plus Shadow Flare, Smoke Bomb, and Healing Surge as my 4. In some cases I might leave off Smoke Bomb or Healing Surge in favor of taking the other mage spell.
If you're considering a respec, you might want to use this calculator to distribute your points ahead of time. I've found it to be a lifesaver for those times when I'm considering a new skill/ability set.