ToME: the Tales of Maj'Eyal

Title about sums it up. Light immunity really hurts on a Sun Paladin, especially if you're trying to go for more of a caster build. Some light resistance penetration would really make chant of light more attractive for such builds.

What really hurts a sun paladin is light affinity coupled with light immunity. Especially sword and shield. They can't stop hitting for light damage without shutting down their own defenses.