Set Bonus Problems

So, I've played PSU on the Xbox 360 for a long time, but I have never known about set bonuses until a few months ago, but I never tested them due to liking certain set ups. Recently, I created a new Hunter (A CAST) and decided his first set would be a Brand and Brandline to grind through Burning Plains. After a while, I unequipped the Brandline to see if I would do less damage I didn't. Same damage on the same enemy. I was wondering if there was a known glitch or if there was a mechanic I seem to be missing on set bonuses :-?

I believe this feature was only available in the online version of the game.