This shield grants the paladin a +1 bonus to AC, this bonus is in addition to the shield's normal bonus to AC. Each time the paladin gets a sacred oath feature the shield provides a benefit:
3rd level: Faith Breaker. As bonus action you can add the shield's AC bonus to your next melee weapon attack. If you hit, the target must succeed on a Dexterity saving throw against your spell save DC or be knocked prone. Once you use this feature it recharges the next dawn.
7th level: Avenger's Grudge. Once per turn when an enemy misses you with a melee weapon attack, the shield gets a charge of vengeance. When the shield reaches 4 charges, your next melee weapon attack inflicts 1d8 force damage and the charges are consumed. The shield maintains a charge for a minute.
15th level: Faithful Defender. The shield grants an additional +1 bonus to AC.
20th level: Relentless Storm. As long as you don't use your avenging angel feature but it is still available, using your action you briefly summon your wings to leap up to 30 feet and land in a 5ft free space you can see. When you land. each creature within 10 feet in all directions must make a constitution saving throw against your spell save DC, on a failed save a creature suffers 3d8 thunder damage and fall prone, or half as much of that damage on a save, but no other effect.
Shields require the Utilize action to Don or Doff. You gain the Armor Class benefit of a Shield only if you have training with it.
Notes: Bonus: Armor Class, Combat, Warding