Humans vs. Undead

It's not about the troops. As a Human, you definitely need to get Antimagic or, at worst, Purification; otherwise, he'll defeat your troops with your own Paladins.

Berserk doesn't work on Paladins, and finding Subjugate is difficult.
However, Light is definitely a good skill to develop for Humans against Necropolis; you can even learn Storm Wind against Ghosts, Vampires, and Dragons.
You can separate the first Paladin to heal your own troops or remove retaliation; if you have many Paladins, it might be worth dividing them into two stacks, although you need to assess the situation.
In principle, there are two main approaches: a cheaper one is Dugald with good magic resistance and a defensive playstyle, or Axel with a focus on attack and, in general, also with magic resistance.