To elaborate, take the basic Two-handed Sword as an example, which has a speed factor of 10. When you issue an attack command to a character with 1 APR who's wielding the weapon, the point should be set to the end of the 6th (6 / 1) second in the round, however as the attack animation itself takes 1 second, in order for the attack to complete within the round, the game will allow the character to start attacking at roughly the end of the 5th second (or the beginning of the 6th second) and finish the attack animation just at the end of the round.
Now let’s take a look at a level 13 fighter with 2 APRs wielding the same weapon, s/he will initiate the first attack at the end of the 3rd (6 / 2) second, whose animation takes up 1 second, the fighter then pauses 1 second, then starts the second attack at the end of the 5th second to finish the round.
So what happens to having more APRs? There’re weapons like Belm that give +1 APR, an Improved Haste doubles APR, and there’re Greater Whirlwind High-level class abilities (HLA) that set APR to 10, the maximum amount the game allows. Well, you’ll never exceed 5 APRs no matter which weapon combination you choose or how you wield them, as for IH or GW, the game actually splits one round into two (3 seconds each) and doubles the attack animation speed (0.5 second each) under their effects. Image a fighter wielding the same weapon activates GW, for the first 3 seconds, s/he has 5 attacks to complete, the animations will take up to a total of 2.5 (0.5x5) seconds, assuming no pauses between them, so the speed factor has only 0.5 second period to factor in, which is almost neglectable. Speaking of GW, the noticeable delay after the HLA activation will surely make its effect go off before the 10th attack finishes, a slight oversight...
To sum up, Speed Factor is notable for characters with low APRs, but matters less for characters with high APRs.
Things that affect Speed Factor:
- Weapon type
- Weapon enhancement level, usually is equal to the SF bonus
- Weapon proficiency, High Master -1, Grand Master -3, Two-Handed Weapon Style -2 or -4
- Class kits, Kensai reduces SF by 1 every four levels
The game also rolls a random initiative factor each round so that even with a worse speed factor, attack can come first.