Random assortment of potential ideas.

Hard angle turns for in flight spells. Delayed activation on spells. Aura's that either buff or damage. Projectiles that can only contact the target and just phase though everything else. Non-visible light spectrum access? Manipulation of ambient light sources. Light based pseudo-clones.

Avenues of thought; You can either play up the Light = Holy aspect, or you can mess around with light as a particle/wave formation.