It's a fast poke. For example, during wakeup, if your opponent hops behind you, that leaves you BT, so BT H+K is a good option to try and hit them with it. Or after 44K, it leaves you at -3, so if you think your opponent is going to throw you, use BT H+K on them.
Free Step Dodge
Saber
Saber
It's also a relauncher. On a BT opponent, do 214P, then H+K will relaunch, then 6PKK~P.
Other than that, there's not much use, but keep in mind, not every move in a moveset is necessarily useful.
Other than that, there's not much use, but keep in mind, not every move in a moveset is necessarily useful.