The erratic behaviour of henchmen imo is due to new A.I techniques implemented by the developers in GW:EN heres my theory as to the A.I techniques used behind the brains of the henchmen.
1) Olias often just stands their with his huge minion army whilst your busy fighting and need his support. This is due to his 'neural net'(think creature from Black and White) which Olias is developing. After 10 minutes of 'learning' from his fellow henchmen Olias will then charge in as to absorb any late-battle spike damage. He will then send the minions in who use the neural net to mimick the fighting style of fellow melee henchmen, without their skills obviously.
2) Mhenlo
Mhenlos A.I is based on the concept of ' the best defence is offence' he is hard coded to decide his best bet is to focus on wanding the mob to death rather than wasting time healing. He uses a 'state machine' to decide when healing is appropiate, this is usually triggered when: AliveTeamMembers<=2.
If anybody else has a better idea as to how the A.I works lets hear it
