i rarely run into many problems holding aggro in AK, even though i'm normally running with DPS from my FC who are in full DL or AF2 with relic +1 weapons. (i only have ifrit weapon personally and a few pieces of DL)

in part thats because the DD know to hold back till i secure hate, and in part due to my opening rotations.

i start by making sure kill order is marked, so everyone is on the same page as to what order to attack in, i then tomahawk target 1 on my way in and flash as soon as the group are close enough, i then use overpower 2-3 times, making sure every mob in the group is being hit. target 1 then gets 2x BB combo and i use overpower again (flash if things have been slept). at 50% heath, i hit target 2 with a BB combe. i swap to final target when target 1 is at 15% health and use a BB combo working backwards through the order to target 2 as DD kill off target 1, i then use flash the moment target 1 is down.

for me, target order is for the DD to follow, you're marking which mob you want their focus on, it doesnt mean YOU as the tank have to follow it, your job is to keep everything smacking you in the face and no-one else. if you break your attacks from the order to do that, there really shouldnt be a problem (as long as the DD are following it!)

provoke and tomahawk is normally enough to get any runner back to you, provided no other DD is targetting it as well, once its in range overpower and flash should keep it there long enough for a BB combo.

As i said, this does mean the party need to understand to follow the kill order and not go insane right away, but if you explain that the moment the dungeon starts i've found most people are ok with that.

good luck, hope that some of that helps.