"Hourglass" support in Temper Weapon increases the time between empowered attack triggers

The support gem "Hourglass" works unintuitively. One would assume that the hourglass support would increase the cooldown of Temper Weapon (it does not). However it adds a cooldown between the triggers of attack empowerment. And you lose your empower stacks even if you attack during its cooldown and the attacks will have no effect. Only one attack every 8 seconds will combust