Completely agree it is a combination of both. While your business training is needed so you know to keep the company first it is all communication/interpersonal skills. That is why they don’t just send anyone to make deals but usually people who are charismatic. Business knowledge or just knowledge of the product in general helps during the negotiation phase and any technical questions that may arise but it is not always this way. I have had some companies come and demo products in groups of two, where one tried to sell the product and the other handled all technical questions and also did the demo. I guess it varies?