The Angel appears to be attempting to rally support from the local villagers and soldiers. Stop him and show him who's boss!
The Angel is located in area where Frantic Frigate will be.
After defeating the boss, player receives a Power Cube as a reward. Player cannot defeat him second time.
After Nemesis update if player has access to Frantic Frigate and World Map then he cannot fight this version of the Angel but instead the Nemesis Angel. In this case the first time you encounter the angel he will continue to have the lower level health and the reward will continue to be the Power Cube rather than the first of the rotating rewards.