I agree with SurpriseGoat. A small shop custom maker has to make the knife, sell the knife, pack the knife, ship the knife -- and he's working on batches of other knives, going to shows, stopping at his computer to handle correspondence (often a low priority). Dead last priority is disappointing a customer, but ... there's only 24 hours in a day.
Playing ping-pong by email doesn't really help, especially for minor questions. Once he shipped the knife, what does it matter why that took so long? I understand the wish for instant gratification. For me, that moment occurs when I make the deal for the knife. When it arrives, then I get to play with it.