Evasion doesnt do jack in this fight so probably avoid dunban. Lorithia has lots of ether damage so thats something you need to deal with. Its possible to run a setup where quick meter build and revives allows you to outlast her but that can get complicated. Lorithia is not kind to those who are underleveled either. I had to be 5 levels avout just to have a close call when I did it. Theres also YT tutorials but you probs dont want spoilers. (Also you'll pay for your insolence.)
I've never had any issue with this boss with more ether-focused builds (melia, riki, and ether 7 are great). I didn't even realize it was notorious for being difficult until after i had beat the game lol.
Is your level high enough? XC is not a hard game, usually it's just a matter of having a high enough level, decent gear and a balanced team... or Shulk, Rein and Dunban