Suggestion: Spellcraft for Paladins and Rangers

[Blackman D]

warlocks have spell like equivalent invocations of 9th level spells and get epic spells, so they are definitely full casters

[Hoihe]

Just like they only get half the spell progression of true casters, they only get half the progression of Spellcraft (30 points for 15 ranks).

But they're not half-casters. They're full casters – 3, just like they are in Pathfinder.

They only get up to 4th level spells. That's a half-caster. And them getting full CL is a BG-custom change.

In the case of both anointed knights and warriors of darkness, they perform more ritualized magic that enhances their human form, but it is still magic. In both cases, therefore, these classes are considered true casters, because their class features and purpose are derived from the pursuit and practice of magic.

How are you distinguishing this from other classes' growth in magical potency? The two PrCs here mix magic oil (or in the case of CoC, are apparently "more" elven than other elves); casting classes gain access to stronger and stronger magic over time. Paladins and Rangers must prepare their spells ahead of time, like Wizards, Clerics, and Druids; what's different for group A from group B?

The flavor of the class. Paladins and rangers are not magic-users first. Again, they are half-casters. Spellcasting supplements their primary duties, but it is something they do on the side. The only paladins in pnp that get Spellcraft are mystic fire knights and magic domain paladins, who focus their duties more specifically on magic.

Anointed Knights and Warriors of Darkness are entirely flavored around magic. Magic is how a character enters the class, magic is how they use their abilities, the study and practice of magic is central in their lore and purpose. They do not cast magic in the form of spells, but they are mage classes nonetheless.

Perhaps giving spellcraft to Divinate, the spellcasting focused paladin only?