It is no secret that the Harvester is the best pick for Pyro’s melee slot, bordering on overpowered. A competent Pyro using it can be incredibly difficult to kill, due to the weapon’s incredibly strong combination of healing and critical hits.
I’ve seen suggestions that propose removing either the healing or the crit effect. And while these nerfs would make the weapon more bearable to fight against, I believe it would also leave the Harvester in a neutered and unfun state, with no alternative to those who enjoy those separate aspects of the Harvester.
Instead, I think the best outcome would be to split the weapon’s strengths (its DPS and healing utility) into two separate melee weapons. That way, both aspects of what make the Harvester effective are preserved, but in more balanced and focused forms.
While I don't know the specifics of the weapons themselves, my general idea was that the DPS-focused weapon could take inspiration from the cut Branding Iron concept for Pyro, while the utility-focused weapon could remain as the Harvester, emphasizing healing over raw damage.