I upgraded my Maskeraith's cloak to the ultimate ability which gives me a speed and attack boost when I use it, but when I activate it, it says I get the speed and attack boost, yet I move at the exact same speed, and I've never tested the attack boost.
Maskeraith cloak speed boost does nothing
The speed and attack boosts are, I believe after having used the ability quite extensively in Vanaduke Wheel Launcher areas, an increase to attack speed and attack damage.
However, with Drakon's upgraded Firestorm ability, at least one of the 2, it does have a movement speed increase on it. My friend Pyrosparker uses it a lot in Vana just to get to places even faster than he already moves wearing full BK set and having medium MSI on his drakon.
I know for the Maskeraith's Deadly shadow cloak, definitely the attack damage is boosted, and i'm pretty sure the attack speed is boosted because I'll tell you when I use Deadly Shadow Cloak to take out annoying Gun Puppys or Rocket Puppys, I usually can 2 shot them like lightning. >.> in a full party, 3 or 4 hits, still pretty fast and damagy, can kill them with my lvl 10 Glacius.
I think the only improvement here would to have better clarity as to what the speed increase was supposed to mean, and if it meant MSI, then yes, the MSI is quite lack-luster as I don't seem to notice any boost in movement speed either.
If it's supposed to refer to ASI, it might be nice to have a quality of life improvement there, and get some clarity on it in game with a better text description of the ability, or a different icon denoting its effects.
I don't think that's a bug; the speed icon just refers to attack speed, not movement speed. The same icon pops up if you use Drakon's Frenzied Firestorm.