Church Assassin
There is no such thing as a Church Assassin. Not only is such a notion anathema to the Archangels and their collected teachings, it is also contrary to the very mindsets of their loyal followers and agents. Even if one sad misguided fool believed they were sent to secretly slay the unrighteous, who would they receive their orders from - certainly not from the Church hierarchy.
The closest that the Church comes to such people are the righteous Urielite and Gabrielite Inquisitions, who seek out wrong-doers in the church, try them publicly in full view of their victims, and then execute them. The martial Michaeline chapters, who have such fierce reputations amongst the sinners, fight directly and overtly against foul armies and dark coercive forces of evil.
A Church Assassin, if there could be such a thing, would need to have the fanaticism of a Gabrielite, brutality of a Michaeline, vengeance of a Urielite, heresy independence of a Sammaelite, unquestioning self-faith of a Raphaelite, and the high-handedness of the Inquisition. Clearly an Assassin who claimed to be a follower of any of the Powers of Light would be in violation of all five of the Holy Virtues of Justice, Redemption, Truth, Faith and Wrath.
This "Hymn" is thus clearly apocryphal:
I am a nightmare walking, psychopath stalking,
King of my jungle; just a priest talking.
My life is a firecracker, quick is my sword;
That was your last chance, your soul will be called.
My life is violent, but violence is life,
Peace is a dream, reality's a knife.
My office, my honour, my Angels, my all:
With my duty upon me, the demons shall fall.
But my true mission is holy revenge.
You aren't in my sect, so you aren't my friend.
Wear the wrong symbol, and your life could end.
Homicide really makes my weekend.
Madness, insanity, live in profanity,
Then some fool claims they understand me.
Give me a break, what world do you live in -
Death to your sect: guess my religion.
You had better be good, so start praying now.