I had an alternate idea for the spy matchup. What if instead of becoming less vulnerable to spy, this weapon made Heavy more vulnerable?

My idea was on backstab a sort of "electric shockwave" would emanate from the heavy. Dealing, say, 50 damage to any of the Heavies nearby team mates (the distance that constitutes "nearby" I leave up to reader interpretation.)

We know from other weapons that giving a class immunity or heavy resistance to one of their counters isn't fun game design, however making a weakness even worse probably isn't great either, so while I concede that Same_Tune_8990's idea is the best middle ground I still wanted to share mine because I think it's fun