As mentioned earlier, for the Item of Power, the main question is "what do you want it to do?" If lightning control is all you need, then tying it to Channeling: Electromancy will be sufficient (with a +1 Item of Power rebate, this adds up to a -1 Refresh item. If you want it to be less versatile but less draining, you could instead replace Channeling with Breath Weapon (Lightning), for the same cost. If you want it to be more versatile, you could tack on Ritual: Electromancy, allowing more fine control of electricity in the surrounding area through thaumaturgical rituals. If you want to add a protective side, it could give him Physical Immunity to electricity only.
Otherwise, you could attach other powers from Zeus's purview. One or more of the Inhuman suite could, of course, be appropriate. If you want to tie into Zeus's nature as the majestic king of the Gods, you could give him Incite Emotion: Awe (or fear). If you want to tie into Zeus's shape-shifting seduction schtick, you could group in some Shapeshifting and/or Modular abilities.
As for the ectomancer, it's true that Ritual: Ectomancy doesn't offer much by way of combat ability. You could supplement it by adding Channeling: Spirit (to represent ectoplasm-sculpting ability learned from dealing with ghosts), though that might hew a bit closely to necromancy for some Wardens. Otherwise, just give him skill at Fists, Weapons, or Guns, and a couple Stunts to supplement.
Other appropriate Powers for an Ectomancer (per Morty's writeup) would be Ghost Speaker and one or more Supernatural Senses attuned to spirits and the like.
