Pretty simple, if he wants to be a 'Water Bender' then give him Channeling (Hydromancer), if you don't want to use Focus items then convert each into a Specialty (equivalent refresh costs for both). The difference being that wheres with Foci he could go +5 Offensive Power Water, you can't do that with Specialties, you'd need to stagger back and forth between Water Power and Water Control with Specialities (so one at +1, the other at +2, then both +2, then one to +3, etc.)
He wants to use Fists to Evocate? Have him take a Stunt which allows him to replace Conviction or Discipline with Fists (not both).
As for the fight scenario, he would use his Water Attack and hit or miss. If he hits and does enough damage then the player takes an aspect. Even if he says "I dodged and hurt my shoulder" (which I don't entirely agree with) it would be a very reasonable to Guess or Declare that water came close enough to him to at least make him DRENCHED. I'd probably grant a guess which used a Fate Point, and the declaration could just be a contest between the two relevant skills to determine if he managed to avoid the water or not. Once the aspect is on him, you can tag it and do a maneuver to FREEZE the enemy, getting the bonus. Of course, he could always just do the maneuver right from the start if he wanted and, if successful, explain it that way.
Anyhow, he can't just say "Even though I missed I get the aspect" he has to play by the rules. This sounds like a player who is digging a concept without fully understanding the game yet, once he knows exactly how aspects and maneuvers work I expect he'll better know how to apply it.