Why didn't you give Fire to Jahan? You're right, Fire is great. I knew I'd be fighting a lot of undead, at least in the beginning of the game, so both my mages got Fire. Jahan and one of my mains do great damage. However, the most powerful character is the other main ... Expert Marksman. Special arrows, grenades, skills, so many weapons.
As mr_raider said, the master level water skill is supposed to be pretty good ... Hail Storm. Both my mages will get it at level 15. After that, I'll get them up to 4 in Fire, so they also have Meteor Storm.
The tactician guide on Steam leans toward Hydro over Fire for number of useful skills, but to be honest, I use Fire more. Of course, I'm going through Hiberheim at the moment.
