Hi there,

Im trying to upgrade my Paladin's Sunsword so that instead of attacking with STR it would use CHA. This would kind of replicate the Hex Warrior hex weapon, but I want it just for this single weapon. 

Is there a way to homebrew a weapon in the toolset to use CHA instead of STR for the attack and damage rolls?

Nope. You would have to make it as plain text and and the player would have to customize the attack & damage modifiers your represent the alternate ability score.

Thanks for the reply. Nice to know I'm not crazy :)

Is there a way to make Hex Warrior a Feat, maybe?

Nope. (And even if there were you cannot attach a homebrewed feat to a Magic item.)

The Hex Warrior features ability to designate a weapon as a Hex Wrapon (and therefore use Cha instead of Str/Dex) is actually tied Specifically to the existence of a class feature named “Hex Warrior.” But you can add that feature to any subclass for any class and it will function the same way. It just won’t include the proficiencies unless you add them as modifiers.