Rapid Assault (Raider) Why do I sometimes get a "Onslaught" buff? +actually attack even faster?

Hi there fellow gamer.

I choosen a Raider this time and picked Rapid Assault to constantly have onslaught going for me.
This is what Rapid Assault does or am I wrong..?

Now I noticed I sometimes get a "Onslaught" buff which confuses me quite a bit.
I think it might be due to "Graceful Assault" which triggers onslaught with a 10% chance on kill.
But why would I get this when I am constantly running onslaught?
And even more confusing, I do actually attack faster when this buff is up.
WHY..? :c


Here is my passive tree.
https://pastebin.com/vWjFxj61

Appreciate your time to enlighten me

TYTY

Rapid Assault gives you permanent Onslaught. You don't see the buff, but its there.

You can check your character profile during combat to check whether your movement speeed or attacks per second is actually changing. I don't know what masteries you have taken, but you might have got some increased movement speed if you haven't been hit recently or frenzy charges increasing attack speed, which could be confusing you.

"

Rapid Assault gives you permanent Onslaught. You don't see the buff, but its there.

okay so thats how I thought.

Yes I do have some increases in attack speed from other sources as well, but the point is that I actually do get a "onslaught" buff icon (occasionally). And when this happens it feels like an additional onslaught buff (but this might happen due to other sources)..

Edit: Yes after more testing it seems that even tho that buff icon is popping up, movement and atk speed is not additonally increased. Still disturbing :D