MC (Angel) keeps dealing 4d8 Holy to entire party

For some reason when holy sword is active, my Angel MC Fighter deals 4d8 holy to entire party everytime he kills a monster. He is equipped with Banshee’s Heart, can’t help but wonder if there’s some bug between the on-critical effect of BH and killing an opponent. Also have feat to auto-dazzling display on a kill, perhaps that might be source of bug?

Update: just killed an ancient crystal with sword active and this time did not deal damage to group