Chivalry is a short spell list that a lot of templates lean on: Consecrate Weapon to match your damage type to the target's weakest resist, Enemy of One for a large single-target damage increase, Divine Fury for the swing speed, Holy Light for area damage, and Remove Curse and Cleanse by Fire for the effects that would otherwise force you to disengage.
Skill level controls both how often these land and how long they hold. At 100 the longer-duration effects need recasting mid-fight; at 120 they are far more dependable, which is what makes Holy Light usable as a real clearing tool rather than an occasional one.
Chivalry also requires positive karma to cast, so keep an eye on that if you are running it alongside Necromancy.
This legendary scroll raises the cap for one character and is consumed on use. It can also be fed to a trained pet to lift the same cap on a pet that uses the skill.