It's a fairly aggressive set, but the main weapon requires steady aim, making it suited for veteran battlers. (gonintendo.com)
Hip Fire Kills — Get 150 hip fire kills using Steady Aim (wolfsgamingblog.com)
Like your gadgets you can only take one but there's a nice selection here from the more usual Steady Aiming to the Bad Ass Perk which halves your health in return for earning twice the XP. (wolfsgamingblog.com)