Any reason you have no Law Devotion? That +X to hit translates to damage when used with Power Attack, and AC is also great.
If he has allies, dip into Crusader for Iron Guard's Glare and Shield Block, then take either White Raven Defense -> Clarion Commander or Devoted Bulwark -> Faith Unswerving. These two tactical feats are fucking awesome, and both are fitting for a "leader" type guy. Iron Guard's Glare + Law Devotion = net +5 AC to a lot of allies. Shield Block is also good for protecting someone who is about to die.
As for making him more powerful, there's the standard "DMM persist a bunch of spells that kick ass." Other all-purpose suggestions:
-Ditch Imp. Shield Bash, you're focused on AC right now, not TWF. Just don't shield bash.
-You could also afford to lose Shield Specialization and Agile Shield Fighter, the +3 benefits to AC are replaced and more by Law Devotion.
-This removes the need to take Ordained Champion, so let's go with something a little more fun, how about some good old fashioned Church Inquisitor? Okay, less fun, but more spells, which is what we really care about.
-I don't seem to see any Prestige Paladin. This is an NPC, so unless he plans on gaining some levels, you might wanna ditch the mounted combat.
-If you dip Crusader, you can pick up thicket of blades if you want. Also this lets you use Cloistered Cleric.
So if you go with my suggestion, you get
Cloistered Cleric2/Crusader1/Church Inquisitor2/Crusader+1/Church Inquisitor +3. This will get you Thicket of Blades, which is useful. Loses a number of caster levels equal to your ordained champion build. If you need more feats, you could go for more Ordained Champion.
For feats, Try: Law Devotion, Power Attack, Extra Turning, Holy Warrior, Knowledge Devotion, and either White Raven Defense -> Clarion Commander or Devoted Bulwark -> Faith Unswerving. You may or may not want Combat Reflexes in here, and if you do, you'd also benefit from a Spinning Sword (Secrets of Sarlonna), but at that point, you've probably got too many feats and you'll need to take Ordained Champion again.
This build is focused on granting his allies, who probably have a low AC, a much higher AC. He can grant adjacent allies a +4 with Iron Guard's Glare, shield block grants them an additional 6, and his tactical feats are both centered on party support.
Noting that you're an old character, you'd probably be best suited to using the White Raven tactical feat instead of the Devoted Spirit one, simply because it requires less of you putting your ass on the line and it's Cha based, which you get a bonus to.
For spells, you get 4th level spells, so toss a Holy Transformation or a Divine Power out. If you focus on losing no caster levels whatsoever, a Righteous Wrath of the Faithful is win.
Sorry for the rambling, but there's a lot of useful suggestions in there.