Blackguard Variant

Reading the Blackguard description in DMG it says:

"Sorcerers, Wizards and Clerics who become Blackguards favor dealing with fiends especially"

The problem? Blackguards are a good choice for those classes as much a rogue or a fighter is. Which means is a very bad choice unless you dip and take Practiced Spellcaster.
Doing some research I found this very interesting variant.

It simply gives 5/10 progression in any spellcasting class and removes unique spells. Like it should. Much like the Dragonslayer.

Further support for this is found in Unearthed Arcana. The prestige Paladin/Bard/Ranger all get spell progression instead of unique spells.
And personally I can't remember a prestige class that gets unique spells and is still great. Assassin maybe?

Also I checked the Blackguard spell list in Spell Compendium and no spell he gets is unique. Every spell I think is from the Cleric spell list mostly.

This will save you the trouble of making new spells for him and a custom GUI also. And well it will make Blackguard useful for every single class to take all 10 levels.
If not well then you could make it an optional download which is worth it I believe.

You aren't serious are you? Give an already ridiculous class 5/10 divine progression?!

Well I wouldn't call it ridiculous. Most people find the Blackguard both in DnD and NwN2 very weak. 5/10 spellcasting is a "fix/upgrade" that is proposed on many forums.

Dragonslayer does a similar thing to what I propose. Knight of Tierdrial offers full BAB and spellcasting without any loss (for Clerics) unless the requirements count.

Also if you are talking about Dark Blessing and Turn Undead (Divine Shield/Might) benefits, a Cleric/Paladin is a MUCH better choice with no requirements also. The new Hexblade will also be a nice way to get CHA mod to saves also unless it's capped by level.
Also Clerics will have to raise both Charisma and Wisdom to get any benefit.

What I propose is to make it a good choice for any class to take all 10 levels and well you could cap the Dark Blessing/Divine Shield by level.

An optional download is not a bad idea I think.