Is Genie Paladin too strong?

I'm imagining a thrown weapon completely shutting down even the largest, most powerful enemies. I cannot believe the designers wanted an ability that lets a level 3 paladin force an ancient dragon to plummet out of the sky.

I don't like designing against my players, but I don't know how to have good encounters in a tyranny of dragons campaign where the paladin can completely shut down a monster with a hit and gets to give out resistance to elements.