In lane phase at least, playing against that ability feels absolutely godawful. He seems to just auto-win almost every trade because all he has to do to negate your entire combo is press e, just for him to immediately follow up with his point and click stun.
I'm not pretending like Pantheon is broken in any sense here. I know he's early game focused and he falls off late game, and there are plenty of ways to play around him as the game goes on. I'm just saying that his e giving him full immunity on a basic ability feels like total shit to play against during lane phase and it being damage reduction instead would feel a lot more fair to play against in my opinion.
Maybe I'm just being QQ here, but that is one of the spells I absolutely hate the most in this entire game.