Provided you have at least one phial filled, you can now use a Savage Axe Slash, while amped element discharge is readying, to activate Power Axe Mode. For a set time afterwards, axe attacks will be further enhanced depending on the type of phial you are using.
Power Element Phials: Enhances elemental damage of your axe attacks for a longer period of time.
Impact Phials: Enhances physical damage of your axe attacks for a short period of time.
Power Axe Mode will consume phials while active and, will end once all phials have been exhausted.
You can use a slinger burst while in axe mode after your attacks, or while guarding in sword mode. You cannot perform a slinger burst after an attack knocks you back significantly, but if you boost the charge blade's guard capabilities to prevent knockback, slinger bursts will become easier to perform.