If there's one thing Dungeons & Dragons was missing, it would be a system of magic based around strange women lyin' in ponds distributin' magic swords. Thankfully, that's been addressed. Like the star pact hexblade article, the new crunch is restricted to levels where you don't normally get to choose. There's also a page of flavor to dish up with it, which could provide a solid foundation for a character to go a-questin'.
At 1st-level, you get a renamed blade of annihilation and a pair of spells that let you deal radiant damage or a lot of radiant damage (and making nearby enemies vulnerable to it). Many of the attacks revolve around dealing radiant damage, but as you ascend levels you can also summon undead handmaidens, blind enemies, and transform into a radiant champion that gains a considerable speed boost and can deal automatic damage once per round.
It's a good variation of the fey pact theme that delivers its own, solid concept of a questing knight, and will be something I'll use when I revisit my failed primal adventure path.