I've been on raids with British police where the suspect has a violent criminal history. They just put on helmets and had shields ready in the van. No guns, no tasers, just batons and pepper spray. On one occasion the suspect had previously gotten arrested for brandishing nunchucks in public, and in the pre-raid briefing the sergeant said "if he comes at you with them, just retreat and wait for him to either knock himself out or tire himself out, then hit him a bit". He was only semi-joking.
It absolutely comes down to better training. Even failing that, I see no reason why a taser could not have been used in this situation. And ultimately if a police officer gets injured, tough shit: it's what they get paid for and they're well aware of the risks when they sign up. Maybe ditching the "shoot anyone who poses a marginal threat" mentality would be good for the police too, I reckon there'd be a lot less power hungry cops in the states.
Riot gear? Use those man catchers the japanese have? Retreat if he doesn't pose an immediate threat to anyone else? Pepperspray?
Other countries manage to detain physically violent people without shooting them. Unless the US is governed by different physics that make steel pipes more lethal I think there's no solid argument why police officers can't just handle the situation the same as everyone else.
Even a warning shot in the air is enough to calm certain situations. Or is there risk of shooting a plane, helicopter, falling bullet killing someone else?
Probably the guy had no intention of using it as a weapon, but cops do deal with people prepared to attack them, and had only subtle clues that this case might be different. Given that they already had guns drawn, a clear signal, the deafness is almost irrelevant. Either the guy was coming after them, or just not tracking the situation. Only in hindsight is it clear that it was the latter.