Fighter Martial Subclass

Crusaders are zealous, destructive fighters who use thier faith as a weapon. A high Charisma is recommended.

Divine Icon
Starting at 3rd level, you can cause your weapon to glow with radiant light for 1 minute as a bonus action. During this time, it has a +1 bonus to attack and damage rolls. You can use this once, but regain the ability to do so when you finish a long rest.

Radiant Flare
Starting at 7th level, when you activate Divine Icon, you may use a reaction when you hit an enemy with an affected weapon to deal an extra 10 Radiant damage. You may use this effect at a later stage, but at the start of each of your turns the Radiant damage bonus decreases by 1. You must finish a long rest before using this feature again.

Radiant Magic
Starting at 10th level, you learn 3 first level Paladin spells and one second-level one. You can cast each of them once before finishing a long rest. Charisma is your spellcasting ability modifier, and your spell save DC is 8 + Your Proficiency bonus + Your Charisma Modifier.

Weapon Affinity
From 15th level onwards, your Divine Icon feature’s bonus becomes +2, and your Radiant Flare’s bonus can be replaced with your Charisma score if you choose. Also, the radiant damage bonus no longer decays.

Magical Skill
Starting at 18th level, you can replace you 1st-level spells with 2nd level ones (or have them as 2nd level versions of themselves) and replace the 2nd level one with a 3rd level one (or have it as a 3rd level of itself).