Adrenaline rush gets bugged when using a Giganto Axe.
It gives the buff but can lower the aspd to what it would be without the buff when refreshing or not giving it when it isn't already active. Switching to another axe fixes it and so does switching axes and back to a Giganto Axe.
I'm guessing there is some issue with the skill and the 3% aspd buff given by the axe at >95 str. It isn't always present, but spamming adrenaline rush 5 times or so usually triggers it.
If u gear the giganto axe and after u warp (teleportation, fly wing, butterfly wing, enter to a portarl) and after again use a skill/item that icnrease aspd (Adrenaline Rush and Berserk Potion) u don't get your full aspd.
Avoid this weapon if u exp with converters/endows: just use for single monsters or similiar
Unfortunately the weapon's script is standard, so the bug lies in the hard code of the game, which means it's harder to fix, it's been reported before but we haven't figured it out yet, until then we're sorry for the inconvenience.