And again, I regard +0 as relevant because of the fact that 1st level characters with less than full BAB ARE entitled an attack.
I see where you are coming from now, but I don't think I agree about the impact on the game. I don't think a 1st level character, under these rules, should get a second attack just because he's holding a lighter, smaller, weapon.
This rule makes levels 1-4 the "learning ground", where PCs are slowly becoming experts with their weapons. At level 5, they are expert enough to use a dagger more quickly than they could before (BAB +5/+1), but they haven't yet learned the same with bulkier weapons (BAB +5 for Standard and Slow weapons).
That seems about right to me, and I like how the extra attacks fade into use (for example, the two attacks with Quick weapons but not Standard or Slow weapons, as shown above for the 5th level character) instead of a glaring extra attack that just happens when the character turns 6th level. With this rule, there's two attacks with Quick weapons only at level 5 (BAB +5/+1); two attacks with Quick and Standard weapons at level 6 (Quick is BAB +6/+2, whild Standard is BAB +6/+1). And two attack will all three weapon classes at level 7 (Quick is BAB +7/+3, Standard is BAB +7/+2, and Slow is BAB +7/+1).
That all seems to balance out nicely.
ALSO, THERE'S A CONAN RPG RULE THAT CAN BE USED WITH D&D....
In the Conan game, weapon length and bulk play a part in how well the character can defend himself. In D&D terms, a modifier is placed on AC depending on bulk of the weapon.
There are three "bulk" ratings in the game: Light, One-Handed, and Two-Handed weapons. This describes how easy the weapon is to wield.
Apply a +1 bonus or a -1 penalty to defense as needed
per weapon category.
So, for example, if two fighters with longswords fight each other, there is no bonus or penalty to AC because the weapons they use are One-Handed, about the same size and bulk, and about as easy to wield. They're in the same category.
It's when weapons from different categories are used that the bonuses and penalties are used.
Say a Fighter with a Two-Handed sword fights a Thief with a dagger. This means the Fighter would get +2 AC against the Thief because of his weapon length. When the Fighter attacks, the Thief would get a -2 penalty to his AC. There's two categories difference, so the penalty and bonus are +/-2.
If the difference is only one catgory, as with a Fighter with a Longsword (One-Handed weapon) fighting Barbarian with a Two-Handed sword (a Two-Handed weapon), the Fighter is penalized -1 AC while the Barbarian is given a bonus +1 AC due to weapon reach.
I think this rule would work well with the Speed Factor rule discussed in this thread.