OK, I've tested this thing and it actually buffs char's attack CD. As you can see on these screenshots, my minotaur had 5.8 seconds CD at 76% buff. After I've upgraded it to 67%, the same minotaur's attack CD became 4.9 seconds, which means that it's CD decreased by almost a second. It's not really easy to see the numbers on mobile(I hope developer will fix thix), but if you look close enough you would
probably see it.
Viewing post in World Eater - Vorish Castle Defense comments
I see. Doesn't feel as if my army is attacking any faster than it has been. But since most of my focus is everywhere else. I would imagine it's hard to see minor differences like those. (Unless you fully max it out and you just watch a minotauress do a 6-hit combo in 2 seconds flat. which would be possibly funny to watch IMO.)