Back again with some more refinements on my thoughts in altering Two-Weapon Fighting based on the input I got from folks answering these posts:
As can be seen, I've a desire to make Two-Weapon Fighting be an equal with Sword+Board and Great Weapon in terms of damage (between them) and having it's own niche (reliable damage and crowd control) without making it too complicated or strong. As it stands in vanilla, it fails to keep up with the other styles on both fronts
For ease of reference, I'll briefly reiterate and expand on a few of the problems that I have with the TWF style so you all don't have to swap between tabs as much:
It starts too strong from levels 1-4 then falls off level 5+ due to abnormally low scaling.
It's disproportionately expensive in the action economy in comparison to it's competition.
What it does is imitated by two separate feats, Great Weapon Master (albeit conditionally) and Polearm Master, but even better and with a base style that grows well.
It disencourages traditional TWF styles of using a bigger and then smaller weapon, leading to silly weapon loadouts (other than lances, I love that look).
To address these issues, I've put together the following alterations to the TWF mechanic. Please don't include the fighting style or feat since I'll be posting revisions of those later if this one works out.
The questions I hope to have answered here are:
Does the mechanic I've presented address the issues I have listed?
Is it intuitive, easy, and fast to both understand and play with?
Is it balanced in comparison to Sword and Board and Great Weapon?
Are there any weird interactions caused from these changes?
When you take the Attack Action and you only attack with a light melee weapon that you are holding in one hand, you can make an equal number of attacks with a different light melee weapon in your other hand. When you do this, halve damage modifiers for all attacks and the second weapon's weapon damage die is a d4.
If either weapon has the Thrown property, you can throw the weapon, instead of making a melee Attack with it.