I have been through the Patent process several times with my father who had a few patents.Your first step is to contact a Patent attorney.They will hook you up will all you will need to do, forms, drawings etc.
Now as to patenting knives, IMHO totally worthless.First the chances of a design being totally unique is rare, and the costs of the process including the patent search are very expensive.And even if you had a design that was unique and did get the patent, enforcing the patent is usually way beyond the means of the average person.Suits have to be done in Federal courts in the offending parties jurisdiction and can take a long time to fight.Also if the Chinese wish to copy them, it is virtually impossible to stop them.
Your better off to make them, market them and take your profits and move on.It takes alot of knives to payoff an attorney.God luck with whatever path you choose.Dave