Well, for shit on... whats the difficulty, higher then Heroic. Well, going up melee is suicide and your primary is fking shit. What you need to do is carry an element for every type of you like to use (like fusion, have 1 of each element). Honestly, going around with Fusion rifle is probably the best. Out of the guns you have, Ice Breaker should be your best pick for PvE. I never took a look at it for PvP, but you could snipe forever, of course, if it did hold up great. Invective is fking crazy in PvP.