Unsure how I managed it, was playing iron banner and I suddenly became unable to harm enemys with my weapons? Normal melee attacks did not work either. I was using Burning maul on my titan and my hammer could still hurt and kill people along with my supers slam attacks, but I would not gain any perk boosts from kills with either. I could still take damage but only through the luck of somebodies attack actually hitting me without knowing I was there. I don't want to get banned for this cause I don't even know how it happened myself, but just thought to let you guys know such a glitch exists.