Dual Blades, "Blinding Feint", scrapper vs. brute

[RikOz]

I've come across an oddity with "Blinding Feint" from Dual Blades.

 

When I use Blinding Feint on my DB brute, it produces a "buildup" graphical effect on the character.

 

This effect does not happen for my DB scrapper.

 

Glitch, or intentional differentiation between the brute and scrapper versions of the powerset?