Everyone still thinks H2H means hand to hand combat? Silly. This is clearly a special speech perk called heart to heart where you can have an engaging conversation with any human character you want.
+1 for H2H. Always want to be a legit ninja in Skyrim, but never had the chance.

Also, they should add in addition to shouts, the ability to just "communicate". Maybe it could revamp the Speech skill tree.
So like when you equip "Threaten", tap the shout button and it will just say something to a single person/enemy like "I'm going to break your neck", and if you hold down the shout button you will be communicate to everyone: "I'm going to roast you all in a bonfire and feed you to the wolves".
And if you equip "Threaten" and yell at followers or friendlies, for example, you will be like "GET THE [censored] OUT OF THE WAY, LYDIA", and she will be like "Hey that's not nice", and you yell back and be like "SHUT UP"

Or when you're in sneak mode, "Threaten" would be like "I'm going to give you an atomic wedgie before I slit your throat", or when you hold down the button you'll be like: "I'M BATMAN" to an entire group; and if your Speech is high enough, it would scare them and/or lower their perception to give you a chance to sneak attack.
Vice versa, if you have "Sweet Tongue" (or something like that) equip, you can mock, play mind games with your enemies while in combat and lower their perception, defence and attack; or if you Speech is high enough you would actually convince enemies to stop fighting and commit honorable suicide.