Varying Attack Speeds
This one would need to be very minor on some units, but scale greatly with others. For example, on melee it would increase their attack speed, but would have a negative effective on their dmg per attack *for balance and logic* since they have less time to build up a good quality swing. For ranged it could be speed affects their accuracy instead of dmg *gravity and arrows tend to not change their dmg potential, speed fired can change how accurate the shot is though*
While the majority of the total dmg is the same *i am sure there is a sweet spot for increased dmg over all though* you would have to likely neglect your other stats a little to achieve it, likely making the squad a glass cannon.
This i feel, for the archers at least, should be tired in with their ammo stat. Otherwise they would only be negatively affected by this one. It would likely make it so their downtime was often but small due to fast reload, but when they have arrows they are emptied rapidly by all the archers firing off a volley or two.
As for the melee, this kind of stat would most help some of the Calvary that people often use to go after archers, such as Mounted Impalers for the orcs. Currently they kill a unit in the archer squad, stand around for a second or two then go kill another unit, two or three times tend to kill the entire squad. With a stat like this they may go right to the next one after the previous one was dead.
The squads without any attack speed stats from skill points likely would be as they are now so as to retain consistantcy and since that speed seems fairly balanced for the majority of them. Which is another big reason I suggested the changes in their attack speed should directly affect their dmg per attack, so that it takes longer to pass the threshold from just different, into more overall damage done to the target.
"To underestimate a Goblin Horde is to stare into the face of Hell and think it to be heaven." ~ Svulnar, The Goblin King