you gain the following:

+1 to str or con.you have proficiency in con saving throws. you get proficiency in medicine.

when attacking an undead of any kind with a melee weapon, you do 1d4 more damage.

as a reaction you can move back 5 ft of movement if you have enough left if an undead of any kind moves next to you(this does not provoke opportunity attack), or you can instead use "holy chant"

"holy chant" usable twice per short or long rest, you may use your action to use "holy chant",it does 1d6 radiant damage at lv 2 1d6 +2 at level 5 and 1d6 +4 at level9 and at level 13 it does 2d6, range:every undead creature of any kind within 5ft f you, above or below, if used as a reaction it does 1d6 radiant damage regardless of your level. it is an AOE attack(you probably already knew that).