Killing a mouse with an elephant gun was about the Red King killing three people with his curse. If you're saying that's what he did then okay. Harry killed thousands.
Did anyone say it was okay? I don't remember saying it was okay.. The Red King was going to kill three humans, maybe four, Thomas is also a descendant of Eb, starting off with killing a then six or eight year old child, I don't remember Maggie's exact age... His spell, he originated it, he powered it. Harry killed the youngest vampire, who was Susan before she turned, she wasn't human when he killed her, that blew back the Red King's own curse on him and his descendants, no humans... Those of the half turned died because they had been alive beyond the life span of a human.. Once the vamp half died, they died of old age, the younger half turned were suddenly cured, they were human once more... So I guess you could say when he wiped out a species, Harry also saved hundreds if not thousands of half turned who were doomed at some point to lose control and go all vamp.. I am not here to say that it was okay or not okay, it is a bit more complicated than that statement makes it out as.
arry did nothing in Blood Rites because Eb squeezed his burnt hand and hurt him to break him out of his rage.
He didn't want Harry to do more harm to himself in his injured condition... But honestly, Harry's reaction in his weakened state was perfectly normal.. It was a very human reaction, he was deprived of ever knowing his mother because this asshole murdered her... He has suffered all of his life because of it, yet no justice for Lord Raith as far as he knew at that moment.. And Eb if you remember also told him not even he, the Blackstaff could bring Raith to justice.. Yeah, I'd call that a very normal reaction on Harry's part.. Emotional, yes, out of control, yes, but normal, that is why we need others to bring us back to our senses like Eb did..
And yes, Butters also did it when Murphy died, and yes, it was a totally normal reaction from Harry. What's more, the Sword knew it as well, it gave him a good burn to bring him back, it worked. If Harry was truly evil, it would have cut his arm off.