Personally I think it has no place in a pretty social environment where the task is to survive together, not burn, pillage, and steal. Besides that, unless it was flashy in some way and not a a test of who could survive the longest without breaking their finger I don't see it be anywhere near interesting enough compared to something like Tekken.

If they got rid / heavily nerfed enchantments and potions, then you might have something because it wouldn't be a potato fight. You don't need stronger / more / unique weapons, all they do is make killing slower or faster. What would be better is an incentive of player skill such as use of enderpearls (get rid of fall damage), possibly give chorus fruit a buff by removing the eating animation or turn it into a potion / item that give the teleport effect.

Another possible change would be dying leather armor to be camo instead of having that giant band. I realize its necessity, but part of fighting is the mind games which is why I wonder what the use of an Invisibility potion is when you can see the armor. Give Spectiral Arrows some function by allowing players to tag enemies who down one assuming that the new version would make everything invisible.

In short, MCPvP is and always will be dull.

The only change I would make is make crystal explosions less strong. It's very annoying to be blown up by a crystal player

The only thing I'd change is knockback. It's too strong!