The Church had to be reconsecrated because the Divine Liturgy is a Bloodless Sacrifice and if the Priest cut his hand the same rules would apply he could not continue with the service.
Yes, some of the laws have to do with blood per se. The Orthodox have a somewhat Old Testament attitude towards the impurity of blood (one of the reason women under the age of menopause were kept away from traditional Orthodox churches most of the time), but would the church have needed reconsecration if the priest had just cut his hand? I’m asking because I don’t know.
Killing is another thing. They had to immediately shut down and reconsecrate St Patrick’s Cathedral in NYC after an usher was beaten to death by a homeless person some years ago.
I know that a man who has killed someone cannot be a priest in the Orthodox Church, which was a problem for soldiers who wanted to be priests. The Catholic Church theoretically forbade this too, but there must have been some way around it, because there were many soldier-priests.
I don’t know if Protestant churches have any way of dealing with this or even consider it. I’m Catholic, but I lived some place where I spent a lot of time with (Russian) Orthodox people, so I’m slightly familiar with Orthodox practice.
In any case, this is a terrible occurrence. I have always expected something like this to happen here in the US - I pray that it doesn’t.