Reformed Blackguard ?

Edvin

If Paladin with low reputation becomes "Fallen paladin".
Should not be Blackguard with hight reputation "Reformed Blackguard" ?
( Or something like that )

After all, is it opposite Paladin kit.
Same class, same rules.

ZanathKariashi

The main thing that separates a paladin from a blackguard is that blackguards have NO restrictions, while paladins have an incredibly strict code of conduct (the forces of evil just don't care, and even if you piss off one of them, their fellows are more then happy to pass you around to work against their enemies and each other).

The 2nd Complete paladin even goes in depth making it clear that a blackguard should NEVER be treat as an evil opposite to a paladin, as they have no relation at all to paladins beyond being a martial class with some divine spell-casting.

Now, because of the way divine spell-casting works in FR, a Blackguard would need to at least pay lip-service to a evil God to having spell-casting, but beyond that, nothing else in the class would be affected by angering their malefactor, since the rest is just training.