For your reference, the following low level spells have no S component and can therefore be cast in armour with no chance of arcane failure:
0: Flare, Light
1: Feather Fall, Hold Portal, True Strike, Ventriloquism
2: Blindness/Deafness, Blur, Darkness, Knock
A couple of points on your character:
Level 2:
Disrupt Undead doesn't do much damage (d6), you might want to take a utility Cantrip instead. Use an arrow when you want to do d6 ranged attacks.
Mage Armour: Forget it. Continue using armour with your chain shirt for the moment. Since True Strike has no S component, you can cast that without failure.
Level 8:
The first level spell is Change Self, which is purely an illusion. It allows you to pretend to be a different type of humaniod. You probably did want the 2nd level Alter Self (can give you gills, fins, wings, etc), but can't take it here.
Level 9:
I'm not a big fan of Great Cleave. Keep track of about how often you actually would have gotten a second or further attack off of cleave. If it isn't very often, pick a different feat.
Level 12:
Consider taking Blur instead of Mirror Image. At this level, you are going to be facing opponents that can very quickly take out 3-4 images. It is doubtfull the spell would last more than one round. The Blur doesn't require S components, and can be cast on other people.
Level 15:
As mentioned, you are limited to a 2nd level spell with the Extra Spell at this level. GMW probably wouldn't be that great anyways, you are only going to get +2 out of it.
Things to consider:
Get Blindfight and use the Darkness spell. When outnumbered, you turn out the lights and depend on your Listen skill (class skill for Barb) to find your enemies. You will only fail concealment checks 25% of the time, whereas hopefully they will fail them more often. With your Uncanny Dodge, you don't give a bonus to hit you when blind either.
Have you looked at the SpellBlade PrC from Tome & Blood? It would allow you to reduce the Arcane Failure chances to zero for the same average hit points as 1 Barb / 1 Sorc level. You would have to use up a feat to get Heavy Weapon proficiency. You would be giving up Barbarian levels though, so it would reduce your number of Rages/day and you would most likely miss the Damage reduction.