The crook was wearing a mask for the purpose of hiding his identity. We need some case or statute law establishing that as giving more weight to a victim being in fear of losing his life or suffering great bodily harm.
We need explicit laws which permit the use of lethal force to defend property in cases of robbery, whether it is by armed or unarmed perpetrators. Specifically, masked perpetrators should be considered an aggravating factor in a robbery and a mitigating factor for a person resisting a robbery by counterforce. Multiple perpetrators even more so.
The store owner was foolish to speak with reporters. They are agents of hostile organizations who consistently oppose any kind of citizen defense against criminal predation.
I would expect the store owner will be prosecuted for aggravated assault. And he might well be convicted of that under the State laws in effect today. That would depend on jury selection.
There could also be a civil suit. That robber who got stabbed looks to have been permanently disabled. Who is going to pay for his long-term care? Quite possibly, the store owner could be bankrupted by this.
"The process is the punishment." We need some major changes in laws.