Did you tried warlord for 2h?I have only def sov, but detaunt looks so good even without +wounds bonus. And who knows how many targets affected by warlord morale drain ability?
About full Bloodlord (7/7) + def weapon from cities - you prolly know it doents stack, but proc appear more often ofc ...
Problem is as the AM you need to put perfect puddles, pump morale, blast Energy of Vaul, provide direct healing, survive and deal with the mechanics at the same time to be worth 1 slot in a premade WB over another RP or WP.
You want pve for the wards and cities for inf rewards. But overall your best bet would be Borc/Swordmaster. Not sure about competitive 6v6, but in WBs you're be welcomed.