I understand that minor berserk do indeed produce the red glow (as with Slimecraw). With Slimecraw the glow seems to be from the elbows down with a pulsing effect. Dark Deal (while similar) appears to be from the shoulders down and does not pulsate. (could be inaccurate as I have not tried Slimecraw in about a couple of months.)

I guess the issue is that the effect literally looks like my character transforms into a pair of pinkish arms. As mentioned, the effect is very jarring and visually unappealing as a core look to the character class. As this is a core ability for the class, the hope would have been that the visuals would have been brought closer in line to the overall class aesthetics.