There are different combinations of talents for each subclass that make them more viable for PvP or PvE. I'm a Titan and hardly ever have a hard time in crucible. Warlocks and Hunters abilities are nice, but it still comes down to being a better shooter and using tactics for the most part. I use Fist of Havoc when I want to quickly eliminate a certain person, group or to stop another super user. You don't really often get big groups to hit with it, which sucks. Defender is great for Control. You can toss sticky grenades and pop up Ward of Dawn over a flag and melee anyone inside without dying. I've fought 3 people inside one once, beat them all without dying and captured the flag. You'll get used to it and get better eventually.