That's afterglow on base level 99 pieces like Aegis. Afterglow on the 119 versions actually serves a purpose,
I'm not aware of any differences in the afterglow effect at different stages. The vast majority of us didn't even get afterglow until after the fully complete versions became available.

Even the first afterglow wasn't just a visual, it did have a status effect (granted to everyone other than yourself). But these effects were specifically designed and set to be a minor perk (in part because they don't affect the user), not an important effect that's instrumental to game mechanics.