Can anyone explain the factors in determining damage dealt on a Raid Boss?

Here is my dilemma.
My main account, level 257, has an attack of 46aa.
One of my mini's, level 96, has an attack of 27t.
DHs account, level 252, has an attack of 780t.

Damage dealt on a level 90 on the main was 7.4aa, the mini was 8.6aa, and DHs was 15.8aa.

Huh?!?!?!!?!?!!!!! What the heck am I missing?

I have sent in a few tickets in the past year asking for clarification but never got an answer, so I figured it might be better give in and ask here.