Yeah I only put some in initially when she was still fighting then stopped also.
The union stuff, the only way to raise the attack more is just to get the higher levels of it. As the first lv has reduced damage, second level slightly reduced damage and third level removes the damage reduction penalty.
But they did not mention what the actual breakdown of how the overall damage is calculated. So with that I reckon it just depends on the stats of your characters.
Yeah, I've gotten the third tier on some unity skills. Brain aspire helps buff me up high enough to just use the assault orders every other turn. I'll have to look into getting the third suicide skill and see if that does enough. Right now I can only do about 150-200 damage per hit with suicide, definitely not high enough for what I need right now.