Titans have Helm of the Inmost Light, which give them 2 perks for their Fist of Havoc. The closest Warlocks has to that is Starfire Protocol, and that gives us 2 Fusion Grenades, that is technically 1/3 of a perk, it should at least work with all grenades. Most of what Hunters get is perks that are given from Weapons, then the same thing that everyone else gets. Heck, Warlocks don't even get Exotic boots.