Awesome character concept! I'd definitely go with either 'Lighting Bolts' (Breath Weapon) or Channel (Air) along with Marked by Power, Inhuman Strength, and Inhuman Toughness (Probably 'The Catch - True Magic' or similar for +1) for a total of -6.
Breath Weapon seems like the easiest way to do 'Lightning Bolts', but Channeling (Air) definitely gives you the most options.
The main advantage in taking Breath Weapon is you just need a high Weapons score. In melee you benefit from your Inhuman Strength and you have a ranged option with Breath Weapon (I don't think Inhuman Strength would apply for a Refresh 8 game, but it might be worth asking your GM). You could probably take Stunts to increase the range by a Zone ('Good Arm' Weapons stunt), +1 to hit or damage, and/or possibly give you the ability to make it an area attack .
Channeling (Air) on the other hand requires you to have either Fists or Weapons to really take advantage of Inhuman Strength, along with decent Conviction/Discipline and probably 1 or 2 points in Lore. On the plus side, you get Enchanted Item Slots, which could be used to boost your Power/Control or be used for magic items/potions/whatever. And of course, you take at least 1 Mental Stress each Lightning Bolt. And of course, you can get a ton more damage when you need to, having the option to attack multiple targets/an area.
Good luck with whichever way you choose. When you finish writing him up, please post him here so we can see how he turned out! xD