So, I've been looking around trying to clarify some of the unspoken rules that people just sort of agree upon in D&D.
The problem I've hit here is how to define how many attacks you have. Do you have a certain number of attacks by virtue of your BAB, which you can fill with whatever weapons you happen to be carrying? Or is your attack routine determined by those weapons, such that you have a "longsword" attack with which you get the appropriate number of attacks with your BAB?
It seems generally agreed upon that if you don't exceed your maximum number of attacks from BAB, you don't need to be counted as TWFing, even if you're using 2 or more weapons. If true, this suggests that you have a certain number of attacks and how you fill them is your business; TWF just gives you extra attacks under a certain circumstance (carrying a second weapon).
But the problem is that TWF implies an alternate view of how you determine your attacks available; the intent of the feat is obviously that you make X attacks with your main hand and Y attacks with your off hand, and each of those is a particular weapon attack. But if we allow the setup as in the first paragraph, there doesn't seem to be any particular reason you couldn't be wielding a longsword and dagger (with BAB +11 for the sake of argument) and attack longsword/dagger/longsword + dagger/longsword/dagger.
Let me break that down, because you can intermix each progression for a different reason. The first series, which you get for having high BAB, works just like a series of attacks you make without TWF. So if you happen to be wielding a dagger, you can use that without taking TWF penalties on that particular attack. Then you get to your off-hand attack; alternating this relies on the vague nature of how "off-hand" seems to be defined in the rules. The intent was obviously so that not all characters would be forced to be right-handed or whatever and to abstract an essentially pointless detail from the mechanics. It also lets players do whatever is most thematic for a particular situation, which isn't a bad thing. The problem is that, since we can define our off-hand as whichever hand we like, and I can't find limits on that, it seems you can do it whenever you want. Which means that you can, mid-full attack, change which hand you define as your off hand (because the feat specifically says you get those attacks with the second weapon you wield in your off hand).
But here's where it gets ridiculous, because if the above is legit, there's no mechanical reason you couldn't just go longsword/longsword/longsword + longsword/longsword/longsword, wielding an unarmed strike in the hand you never use to qualify for the TWF-granted extra attacks. Yes, the second set of attacks takes extra penalties for not being a light weapon, but you can either just change your off-hand designation after your first set OR you can actually wield your longsword in whichever is your off hand (if it has a fixed definition I just couldn't find), but since in the first set of attacks you're not using it for TWFing, you don't take the off hand penalty until the set granted by TWF. This is clearly stupid, because you're fighting with two weapons with one weapon.
So, the question I have is, is this problem resolved within the rules, or do I need to start houseruling? Further, if I do, should I put the priority on keeping players able to use attacks in combination as suggested in the second actual paragraph I wrote, or should I keep priority on simplicity? The two possible schemes I've got in mind each fail to maintain one of these.
