Shadow:
Merge light into shadow
Blindness -> Darken Sight
Radiant Visage -> Eyeless Swarm
Dance of Shadows -> Mantle of Shadows
New Spell Dance of Shadows: +3 to Combat Speed for target unit for (1 * #shard) turns. Or 5, if that's not doable.
New Spell Haze: All enemy units combat speed reduced by 33% for 3 turns.
Arcane:
Merge Ether into Intuition, change name of Intuition to Arcane.
Add to Ethereal school.
New spell Mana Blast: 3x3 does 3 + (40% * int) damage.
New spell Eradicate: does 9999 damage to target enemy. Caster loses next three turns. Can be cast once per battle. Costs 1/2 of all mana.
Split elemental into two schools, Elemental Warmth (Air and Fire), Elemental Chill (Earth and Water). Or Elemental Creation (Air and Earth) and Elemental Destruction (Water and Fire).
Fire:
Remove Flare
Ignite: targets in 3x3 box take (10% * int) + (1 * #shard) damage per turn for 3x turns.
Fire Ball: target enemy unit takes (20% * int) + (5 * #shard) damage
Air:
Suffocate: Target takes 1 + (1 * #shards) damage for three turns, combat speed halved for three turns.
Evade: Target friendly unit gains (20% * int) dodge.
Remove Storm
Remove Greater Evasion
Water:
Grip of Winter -> Chilling Kiss: Adjacent enemy loses next turn and takes (1 * #shard) damage.
Greater Grip of Winter -> Heart of Winter: For 3 turns, all enemies in 3x3 box take (1*shard) damage per turn, and have a 20% chance of losing their turn.
Blood:
Contagion -> Burning Blood: For 3 turns, all enemy units gain 2 combat speed and take (3 * #shard) damage per turn.
Remove Unceasing Labor (+1 mat isn't worth anything)
Spirit
Remove Teleport (broken mechanic, annihilates positional play)
Remove Return (broken mechanic, annihilates positional play)
Mend Flesh: Heals for 2 + (40% * int)
Blink: reduce range from unlimited to tiles within 3 squares of caster.
New Spell (strategic) Cleanse Weariness: adds +3 move to stack for 3 turns.
New Spell Soul Cage: Target unit loses next turn
New Spell Nightmares: All enemy units have 33% chance of losing next turn
With what you've already got and the changes I suggested, I'd actually use magic.