Glaring Spotlight is an absolutely awful card; now you have to draw two specific cards and spend your entire turn dealing with my one hexproof guy? Sounds good, I'll just get my Rancors back and put them on the other hexproof guy in my hand, now that you don't have any removal. If I played this deck, I would hope people side in Spotlights against me!
Sphere of Safety is too slow, against an aggro deck they'll have you dead by turn 4-5 anyways and just burn you out for the rest.
Actual possibilities: Holy Mantle, Verdant Haven, Gift of Orzhova (remember you can cast this without running black) are all valid additions. I think Verdant Haven is the most interesting, as it provides ramp, fixing, ups your Ethereal Armor boost, and depending on the matchup that 2 life may actually be relevant.
Remember what your deck is trying to do. You aren't a reactive deck that should be running counter spells and combos; you're a proactive deck with minimal interaction. Any card that isn't a hexproof attacker, an individually strong combat aura, or a card that lets you get one of those things out faster, you should think really hard about why you're playing it. Your goal against midrange/control decks is to kill them faster than they can wrath the board and start controlling the game, and your plan against aggro might as well be to race them. Siding in Pacifisms and Negates and Divine Favor actively slow down your deck, which in this kind of archetype is a Bad Thing.