Not really addressing this to you, Ryan, but I think it's important to note for people that were hard on you for not initially making the phone call.
Seems like the maker was willing to take orders and payment through email and discuss the issue with the initial knife that way as well. Given all that, the idea that it's on the customer to change the method of contact when communication gets bad is just wrong. It's pretty clear that there was an ongoing email conversation that went dead for five months when the customer had issues. An international phone call isn't a huge inconvenience, but it's still not right to make the customer go that route when there was a clear and open channel of communication available.
OP's email conversation PROVES that the knife was broken before, in 2015. Without the emails, he had no PROOF - where are all those 'pick up the phone' guys now?