What does the speed factor of a weapon do?

(thanks to Althernai for this, I altered some spelling and a calculation, hope you don't mind)
When everyone has only one attack per round, then it's simple - the attack comes at (6/10)*(speed factor) seconds into their round. If you have more than 1 attack per round, then here is what could happen (I am not sure of this, but I believe it's true - otherwise several attacks would have to be done simultaneously and that has never happened to me before).

Let's say your round and the round of your oppponent starts at the same time. Monks have 4 attacks per round at speed factor 0. If you are fighting someone with 2 attacks per round and speed factor 6, here is what happens (correct me if I am wrong): You attack first at 0 seconds. Then you attack again at 1.5 seconds. Then, at 1.8 seconds he attacks you. You get another attack at 3 seconds, he attacks at 3.6 and then you attack at 4.5. Round is over. So:

In other words, take 6 seconds, divide it by the number of attacks and use the speed factor to place an attack within each interval obtained by the division. Your monk has an attack every 1.5 seconds and a speed factor 0 so he attacks immediately at every 1.5*k where k is a whole number. Your enemy attacks every 3 seconds, but he has a speed factor of 6 so the attacks come at (3/10)*6 or 1.8 and then at 3+1.8=4.8 seconds.

This is all highly theoretical and it could be wrong (I made it up), but clearly, when you have that many attacks, speed factor doesn't really matter.

(Other notes) Anyway, the only time when the speed factor of a weapon would be considered as important, is when you're trying to disrupt a spellcaster trying to cast a spell. If you have a very low (as in good, fast) speed factor, there's a chance you'll hit him before he finishes his incantations and thus disrupt his spell.