I always was tempted to add DC to some characters, but in the end it was never worth it.
It is an interesting concept that can make you RP a 'different' kind of paladin.
Melee Weapon Bonus - I think this bonus is downright terrible. It has so many requirements, and it will ONLY work at its full if the character is a CHA based character. I'd lower the requirements to 14 and 18. Or just remove the Charisma requirement, but make it every 6-7 levels.
Lay on hands - Useful, but if a paladin goes DC becomes completely uselss. Maybe some extra effect\cooldown reduction if you already have it?
Divine Smite - Nothing wrong with that! Beside the redundancy if you already are a "smiter"
Divine Wrath - The selling point of the class. you're going deep in it and you don't dip, you want to go 'mainly' on DC because of this.
And yet.. Knight does it better, and gives something extra as well.
Sacred Defense - the 'evil' alternative, the black guard. Gets a Badass dark blessing at level 2 that is insanely stronger than this. Why not a fixed +X that becomes 'dark blessing' at level 11 ?
Synergies:
The divine champion is a PRC so it means you can feel it as a main class after level.. 25 or so?
Martials: Fighers\Swash\Barbarians and their friends will not benefeti from much of the class. The Ab sucks, the smite sucks, and they're going to lose many of their cool stuff.
Warlock\Sorcerers\Favored souls: They're going to get the full potential of this. But they're going to lose A LOT of caster benefits.
Rogues: They can make something fun out of it for sure if it fits the concept. But they'll need so many stats behind it that maybe it will never be optimal.
Harbinger: Harbinger has a nice synergy feat for DC. But.. it works only for 5 levels. and really gets a lot of fun things on the harbinger as a main class. So, 5 levels in DC are what harbingers with divine patronage are going ot invest. Which is good, as they get smite, lay on hand, melee weapon bonus and wrath. And divine synergy. Which is odd, since it's not something the DC gets.
Clerics: They can benefit from it? but just on some very specific build that relies on the DC class. losing tons of caster levels and getting the DC very late due to the requirements.
Suggestions:
-Give a bonus Power attack at level 1. :It is a -bad- feat if you're not a big multiplier crit build. (And even there...) but it's a requirement for divine might and shield.
-Give a "Divine Synergy" feat somewhere. Like 8? 10? 12?
-Lower the AB requirement. A +7 means you're either a martial or you get this VERY late in pre-epics.
-Charisma bonus: Maybe, somewhere like.. level 8 10 12 some feat that gives a soft CHA bonus based on STR or DEX (Whatever is higher) to make the class viable to non cha-based classes. (Like a +2 cha every X levels if STR or DEX is higher than Y)
-Divine Wrath: Add some scaling of CHA to the divine wrath. Everything basically works on Charisma. the main selling point of the class may benefit from it a lot.
-MAYBE add divine shield and might as feats somewhere past level 5. It will give some more reasons to go divine champion and make it worth it.