What's good wording for "souls of people who died of injustice"?

"souls of people who died of injustice"

"Wronged souls" = souls who have been wronged; souls who have had wrong/a wrong/wrongs inflicted upon them.

OED:

To wrong (v.): I. transitive.

1.a. To do wrong or injury to (a person); to treat with injustice, prejudice, or harshness; to deal unfairly with, withhold some act of justice from (some one).

1860 Ld. Tennyson Sea Dreams 168 His gain is loss; for he that wrongs his friend Wrongs himself more.

Wrong (n.)

II. A wrongful or unfair action, and related uses.

9. A wrongful, unjust, or unfair action; a violation or infringement of one's rights; an injury received or inflicted; a mischief.

1795–6 W. Wordsworth Borderers v. 2071 He forgave the wrong and the wrong-doer.

How about the unjustly dead?

The <adjective> is short for the things/people who/that are <adjective> and in this case it's modified by an adverb so it's saying the people who are dead as a result of injustice. The context of an epic poem about a magical lance suggest that the dead are present in a magical way (souls) rather than the lance literally being full of corpses.

Adverbs and other words ending in -ly stand out a bit and having two in proximity could be a problem so maybe change godly to something else like divine. Just because I think it makes for better rhythm to the line, maybe consider took up instead of wielded

He took up his divine lance, filled with the unjustly dead.

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"