Doubt they use the deadly weapon angle. The argument will likely be that the officer feared being incapacitated since he took the taser he might have gotten his gun if he tazed him. Or they will say he was an immediate threat to the public since he was fighting cops and had a police weapon on him. Either way it will come down to a judgement call that the cop was legally empowered to make based off the current laws and we all know that no jury will convict the cops given the circumstances if they even get charged to begin with. hope I'm wrong though.
They need to keep the charges realistic. I know everyone wants 1st degree murder but they gotta prove it was premeditated. Keep the charges winnable so that they can see some actual jail time. If they overcharge them they will walk