Definitely writing a book with undead protagonists. I should bring back the Sinless, write down that setting's details

The Sinless were criminals, sentenced to death. Stabbed through the chest with ritual swords in public executions.
Some simply die, but the lucky are reborn as holy warriors, their memories blank, slate wiped clean. The plain ritual swords absorb their sins morph into unique, ornate blades, their only shared trait being the shining red metal.
They wander the world, hunting down both monsters and sinners alike.

I forget when I wrote this. I was a teen, definitely.

There was something about holy fire, but I don't remember the details.
The Sinless are not teachers (though priests do exist within that religion) but they're respected, and if they need something, it's usually provided without much question.
I think there was something about earning their old memories back if they did enough good, too. A motivator, alongside the "if you don't perform your duties your powers (like 'not being dead from the hole in your chest') go away"