What does (or does not) Hidden Daggers buff?

lastmaxstanding

Can't seem to find a sure answer, just want to know what actually is (or isn't) affected, since it says 'melee' rather than at-will, encounter, etc.

burndownxmas

Essentially all powers except hidden daggers, slam, grand fissure, or any powers that have the description personal power on them like "not so fast" (not sure why considering some of those are melee powers too)