he's a rdm/brd in ballista, of COURSE hes gonna be sleeping you, he has 4 diffrent spells that can! just chug that poison potion, bind him, and shoot him in the head with sidewinder or slugshot.
Whm's are very good in ballista so long as they play like whm's and not try to kill people. With rdm sub and some good spell interruption gear, damage reduction gear, you're no easier to kill than a melee. I think I got my medicine earring for 1k gil. I'll never forget when Nark did rampage on me for 56 damage.