[SPOILER] Lostwind Cliff Armen actions plot hole?

When Armen arrives to scene to save the people from being killed for being Heretics, he does nothing and watches by how they are killed with the arrows. And in the middle he decides to open a shield, but ultimately everyone dies.

Was he in a weakened or confused state to let everyone die? Otherwise he should be strong enough to protect everyone. For me it kind of seemed off place that he would just let them all die and then later turn into a demon.

It would seem more logical that he arrived to scene when everybody was killed and then turn into the demon.

Did I miss something?

He was heavily wounded and still reeling from the fights with the Demon-with-a-long-name Mayhem Legion Commander (and what it did to his head/mental space). He kept trying to reason with them and wasn’t at full strength.

We first saw how wounded he was in Layer Terrace. Thirain even tried to get us to send him back to the castle before Borea’s Domain happened.