First let me say that I’m sorry for what happened to your dog. That away to have to watch and the pain and suffering that you must both be feeling is terrible.
Here’s the hard part: that your dog was off leash really makes it your fault though the Akita breaking free of its leash may be the only mitigation you could expect.
You pull some very nasty rhetorical tricks in your post. You point out the history and roots of the breed and that while your dog has never been in a dog fight you imply that this one surely has. The fact it that your dog certainly approached another leashed dog. Your dog probably ran at it as dogs are wont to do. This would elicit a defensive response.
I have my own biases. I own two pit bulls. They are big chickens despite their reputation. While the breed is responsible for the most maulings in the last 20 years that isn’t indicative of the majority of the members of the breeds that make up the collection of dogs considered pit bulls. In fact, Labs are the most frequent biters.
Breeds cannot be outright banned in WA. Municipality’s must provide a route around said restrictions that is reasonable for individual dogs. It’s possible that this dog would’ve been able to do so if another dog hadn’t run at it.
I’m sure my post will be unpopular since I’m not displaying any hand wringing or howling for blood, as is popular these days. Feel free to pile on.