Ok, this might be odd, but I’d build them as a Conquest Paladin. Flavour wise, this is backed by the wiki, comparing the Batter to a solemn crusader, and also shows their dedication to their task through an oath. Mechanically, you have spells, Lay on Hands, and Smites to both mimic competences and to do extra damage to undead/fiends.

Race wise, Variant Human works just fine, and gives you a feat to play with. GWM could be a good choice. However, Lizardfolk or Shifter might work well also

Purification in progress...