As we've seen on the TG a week or so ago, the offense got buffed and definitely is more favored than defense, and in order to improve all heroes there could be multiple things done.
But on this thread ill specify one thing and explain how it could massively improve mix-up potential and overall greatly improve on hero or another, this change however will not only target the weaker heroes but also the stronger heroes.

Soft-feint into guardbreak (from heavy)
Should be implemented for most heroes that don't already have either a bash on guardbreak input or already have such a soft-feint like raider, conqueror, peacekeeper and kensei
With this change the fluidity of one character can drastically increase while some just a bit and so duels and fights will come down to a moveset, skill and how to properly use it when facing another opponent, knowing they can soft feint into a bash/guardbreak just as you do.

Pairing this with the TG changes heroes like JJ, Lawbringer, Zhanhu and others with almost instant unblockable finishers will benefit the most from this change while Nobushi, Kensei and others without fast unblockable finishers that come out after 1 or 2 attacks wont benefit so much.

Of course this is a suggestions that would be hard to implement and balance around, but some characters like JJ and others suffering from options during attacks could use, ill list some that should get this addition : Warden, JJ, Shaolin, Gladiator, Lawbringer, Warlord, Berserker, Aramusha and Jormungadr (sure the list could go on but i think these heroes need such option to perform even better)

Now there is another option that takes alot of time and that is to rework each weak hero, and when i mean rework, i mean changing 50% to 90% of the hero's kit to give them a viable playstyle