This thread has taken a serious tangent...
Charisma, Wisdom, or Intelligence fighters. We have subclasses that accomplish this with some hefty caveats, Hexblade being the most notable for Charisma. So it already can be done in 5E, but typically it is to allow a spellcaster to be at least somewhat proficient in physical combat. So you have Pact of the Blade/Hexblade or Bladesong to enable Intelligence. These ability swaps come with some penalties. Only certain weapon types are allowed or the swap is only for a limited amount of time or times per day. The problem is not switching the attribute, but all the junk that goes along with it. Dexterity didn't become the god-stat out of nowhere. There are a lot of knock-on effects that come with consolidating stats for classes. Saving throws, armor class, and skills all have a say in what attributes are favored.
My preference for a charismatic fighter or intelligent strategist would be adding a kicker to a regular fighter. The ability to add charisma to damage one attack per round like a minor sneak attack. Additional maneuvers to gain advantage or position enemies to result in a multi-round setup for a big payoff. Make the mental stat add-on not the root of power.
