Silverhair Knights are an order of elite priests of Eilistraee. They are mostly female drow, elves and half-elves, although males are allowed to become Silverhair Knights too. Silverhair Knights pursue a very specific goal: they want to redeem evil drow from the underdark, purifying their souls and granting them the chance for a new life on the surface.

To achieve this, Silverhair Knights train non-lethal combat techniques with their swords, learn spells to incapacitate their opponents without damaging them and generally attempt to use their blessed serene voice to calm down any conflicts before they actually start engaging in combat.

In addition, Silverhair Knights are blessed with the ability to use an unique kind of magic for redeeming someone, for purifying their souls: They essentially consume their target's sins into their own soul, where they are destroyed by radiance and purity - and thus, they are known as Sin Eaters.

Silverhair Knights usually accompany Sword Dancers and Darksong Knights on missions in the underdark. While the others fight off dangerous monsters and demonic servants of Lolth, the Silverhair Knights attempt to calm down drow, try to protect them and to convince them to come with them to the surface, and if they don't succeed, they use their various tools to incapacitate the drow until they can later purify their souls.

Non-Lethal Combat. Silverhair Knights have vowed to never willingly kill any drow. They are specialiced in techniques for nonlethal combat with both their swords and spells, focusing on incapacitating their enemies, exhausting them or otherwise making them give up fighting. They know how to hit their enemies with a sword to neutralize them without using lethal force, how to bring them down to the ground, where they can be tied up, and how to deter them of potentially dangerous reactions.
However, despite generally fighting nonlethally, Silverhair Knights still are respectable and capable combatants, who can easily apply lethal force to kill powerful enemies if necessary.

Blessed Enchanters. The second important tool Silverhair Knights use for nonlethal combat are their spells. In addition to regular cleric spells they know a wide array of non-damaging enchantment spells specialiced for incapacitating and otherwise neutralizing combatants to prevent casualties. Their blessed voice of redemption makes these enchantment spells particularly effective tools, allowing them to overcome even the innate resistance to charming effects drow just like other elves are known for.

In addition, Silverhair Knights can use a special kind of enchantment magic, which is particularly effective against evil drow - they can make them feel the weight of all sins they committed,  which not just makes them thinking about changing their way of life, it also distracts them in combat, makes them unwilling to continue the fight and can even stun them or cause mental damage.

Sin Eating. A Silverhair Knight can perform a special ritual on another conscious creature with an evil alignment, whether that creature is willing or not, to consume its sins, redeeming it and taking the full weight of cruelty and suffering inflicted by it. The ritual lasts 10 minutes and the Silverhair Knight must be touching the target for the full duration. Once the ritual is completed, the target creature feels the weight of all their sins on their conscience, understands the errors it made in its life and regrets its past actions. The target is then freed of all evil, causing its alignment to change to good. The sins themselves are absorbed into the Sin Eater's soul and destroyed by its radiance and purity.

With each sin eating ritual performed by the Silverhair Knight there is a cumulative 5% chance of it failing as it is overcome by the sins it is trying to absorb. In this case, the Silverhair Knight falls unconscious for 24 hours and the target is not freed of their evil. At the end of that period, the Silverhair Knight must make a DC 15 Charisma saving throw. On a success, the Silverhair Knight wakes up, on a failure however, the Silverhair Knight dies and rises as a ghost with the same evil alignment as the target of the failed ritual.