Justice is a fan-made global mod.

How can this be compensated?

Only with -50% HP or something of the same magnitude/equivalent.
I think Warriors were nerfed too much, especially since Archers were buffed. They have different roles; Warriors played well in the final stages, but Archers were needed for breaking through defenses. Now, Warriors have no place in the Necropolis army; stopping arrows are decisive. They need to at least keep the large shield (but the defense can be reduced).

100? That's too little.

No, it's not little. Maybe it's a bit too much, though. The ability is very harmful, and from a mathematical expectation point of view, it doubles health, except for magic.