Some details of it

But can't Final Hit already be used with Dual Guns? I don't really think comparing to Final Hit is accurate purely based on that it is a buff skill.

Also, there is a method to make the clip not be completely empty after use, but I'm not sure if that would be considered an abusable glitch since being hit after using aftershock resets the cooldown and that's a confirmed intended feature.

Shockwave resetting was never in doubt as a glitch; it behaving that way is in the description and triggering its reset is even a training requirement. The glitch on the other hand counter to what the description of the skill says so it's clearly a glitch, even though some would consider it a clever circumvention.