Weapon (Any Simple or Martial), Legendary (Requires Attunement by a Paladin)
You gain a +3 bonus to attack rolls and damage rolls made with this magic weapon. When you hit a Fiend or an Undead with it, that creature takes an extra 2d10 Radiant damage.
While you hold the drawn weapon, it creates a 10-foot Emanation originating from you. You and all creatures Friendly to you in the Emanation have Advantage on saving throws against spells and other magical effects. If you have 17 or more levels in the Paladin class, the size of the Emanation increases to 30 feet.
RollQuest summary +3 weapon. +2d10 radiant vs Fiends/Undead. 10-ft Emanation (30 ft at Paladin 17): you and Friendly creatures have Advantage on saves vs spells and other magical effects.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.