That's a fair point Cero, we are more in the dark for +% damage bonus. Everyone can see that passive crit adds percentage points, if it really added 1%, you would go from 10% crit to 10.1%. That would be pretty useless.

With damage % bonuses we see no difference in stats, but I think we can reasonably assume it actually does what it says in the skills screen. That is, it increases your damage value by 1%. So you go from 200 to 202. It's hard to see small differences in damage by just playing, because the actual damage is very variable, so that's why I say assume.

One difference between damage and crit, is that crit is a percentage chance stat anyway, and damage isn't.