I think @smithkm is on the right path with "unjustly," but "dead" is too passive and neutral. "Slain" is more poetic, but "slaughtered" really makes the wrongness of the deaths vivid and immediate.

> He wields his godly lance, the lance full of souls of the **unjustly slaughtered**

However, this makes it sound like he's killing people unjustly with his lance, and that it's then drinking their souls which doesn't sound like the hero you were describing. So, assuming he's fighting on behalf of the unjustly slaughtered (and not the one unjustly slaughtering them) I might tweak this a bit more:

> "His lance *blessed by the passion* of the **unjustly slaughtered**"