I'll share my experiences and my methods concerning this area of being a knifemaker.
There was a time when I trusted everyone. I would send a client a knife, without payment, telling them that if they approved of the knife, just send me payment, if they did not like the knife, then simply return it. That worked great for a number of years, until...... I sent a Hunter/Camp knife set to a client, and after not hearing from the client after a week, I called. The phone was disconnected. I tried several more times with the same results. I then sent a registered letter, and it came back "Return to sender, no longer at this address" That was over 15 years ago, and I never saw the knives, the money, or the client again.
At that time I instituted a policy of no knives leaving the shop until payment in full is received. Once I received the payment, the knife is shipped, with a full 7 calendar day inspection period for the client. (the inspection period begins the day the client receives the knife). If for any reason the client is not 100% happy, simply return the knife, and I return the payment. After the 7 day inspection period, I consider the knife has a new owner, and my lifetime warranty applies, with the exception of abuse.
Sometimes its difficult for a knifemaker to stipulate under what conditions a knife may be returned, simply because we tend to be very trusting, and do no want to appear anything less to potential clients. But, I can assure all the makers out there, that if you leave a crack in the door, there will be someone who exploits it. As much as I try to give each and every client the benefit of a doubt, I think it is only prudent to protect yourself, as a maker, from being exploited.
We are blessed in the respect that its not common place in our industry....but without some type of return policy, your leaving yourself wide open. Being fair to your clients, as well as yourself may take a little thought, but it in the end your clients will appreciated it, and you will be preventing possible future problems for yourself as a Maker.