This has been a bug for years but its so counterintuitive that nobody realized it
Act 1 merc can equip bows likes Brand/kuko shakaku/raven claw that grant explosive arrows, the merc shoots the said explosive arrow, it explodes visually but there is no damage from that said explosion
it would be awesome if that bug was to be fixed, im a fan of Enchantress builds and this would open up opportunity and make Non-a2 merc less bad haha