It would be irresponsible for me to suggest changes. My knowledge of all the related or affected feats/builds is paltry compared to some. I'm just trying to get you to think about the problem on a wholistic level (problems that this may introduces) rather than a very localized one (how does this solve my personal issue). It's just like agreeing to use new classes or new feats from various supplements. You may be so focused on what you get, you may not see that you've opened Pandora's Box.
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A valid question. It's one that gets asked a lot in MMO's. That answer is that it depends on the context. Consider this: If a certain build needs a 19 to hit, removing that -2 means you've just doubled the expected damage. If they hit on a 2 or better, than the removing that -2 isn't helping at all is it?
Consider another example...a character with weapons that due ability damage or have status effects. If we just consider the damage output of removing that -2, we'd only see a 10% increase of the expected damage. If every successful hit lowers the targets Constitution...then the +2 modifier is a much bigger deal than the expected damage isn't it?
And once you start looking at doing increased stat damage or adding status modifiers to weapon hits, suddenly it's harder to compare the -2 benefit in terms of just damage. For example, if you had a choice of TWF with weapons that do Con damage or THF with a weapon that does Con damage...which would you prefer? Depends doesn't it?
The difficulty in answering these questions is probably why there is no "fix" for TWF or other styles. I'm going to repeat what I said above, if you really want to make TWF "viable" give it something that makes it unique and useful...don't try to make it the same as others or more powerful. You like TWF because of the play-style, so add a change that enhances that style of play without treading on the toes of other styles. The THF should always do more damage...you just should be able to say, "Yes, but I can do X and you can't." And then there should be no easy answer as to which is more important, X or more damage.
Let me leave you with a thought:
You can't fix the game...you can only change it.
Hey I appreciate the caution. That's what I'm looking to do just change it. I'll look into the TWF O.P. stuff you listed! I think I'll start from the top down, then go from the bottom up. Thanks!
That having been said, if I were going to make TWF playable for Rangers, I would give Rangers/Fighters Two-Weapon Defense as part of TWF. I'd also change Weapon Finesse for Rangers/Fighters to apply to all weapons and modify To Hit and Damage bonus regardless of the weapon type.
Why not just dip one level of swordsage and take the shadow blade feat on top of weapon finesse or the feycraft template with a light weapon?
D&D, for reasons not entirely clear, really screws over Dex based Fighter/Ranger builds. Better armors reduce Dex benefit and there are numerous conditions where you lose your Dex bonus, but almost none where you lose your Strength bonus or Armor bonus
Note that I don't think Non-Fighter classes need these benefits. Rogues already get tons of versatility and abilities. Making them the equal of Fighters for damage is fundamentally flawed since nothing allows Fighters to replace Rogues with regard to skills.
Isn't this because Dex is probably the strongest attribute overall?