I decided to make a homebrew dex fighter subclass.

The first thing I wanted to give the player (at lvl 3) is a way to use the dex mod instead of the strength mod on their melee weapons.

What would you suggest I do?

-Try to add a modifier on the feat? If so how would I go about that?

-Give them options on weapons? If so would I have to make homebrew weapons? And if that's the ticket how do I add those homebrew weapon options into the feat mods?

I'm open to ideas, I'm just looking to make an overall fighter subclass that uses dex instead of strength. 

Are you making a feat or a subclass? You started saying subclass but then changed?

You cannot add any modifier to a subclass (or feat) that will allow the character to use Dex for all melee weapons.

You cannot add weapons to a subclass (or feat)

Why wouldn't they just pick up a rapier, like every other dex-based fighter? Literally any fighter subclass can be dex based if they choose to use a finesse weapon.

A rapier skinned as a long sword has lower stats. If you wanted a character like Bronn or Jamie Lannister from GOT a rapier wouldn't work.

Sorry, I'm trying to make a subclass.

What a bummer. I guess I'll just have to punch in those stats in homebrew items, then use those.

Quote from turquoisejosh69 >>

A rapier skinned as a long sword has lower stats. If you wanted a character like Bronn or Jamie Lannister from GOT a rapier wouldn't work.

 
That’s because they used Str instead of Dex and used actual longswords.

The player can just “customize” those weapons on their sheet to display the attack and damage bonuses directly to reflect the alternate stat.