I agree with other posters that this issue is a symptom of a larger problem brewing in the relationship. But it need not cause the demise of your marriage.
Here are some practical things you can do:
1- Forget the knives for a second and take a long hard look at your relationship overall. Be brutally honest with yourself about how compatible you are on a fundamental level and where things need improvement. Seek help in fixing the relationship or things will continue to deteriorate. Successful relationships take hard and constant work -- and they are TOTALLY worth it, in my opinion. She needs to respect your needs/desires/wants just as much as you respect hers.
2- Talk to your wife. Women like to discuss things (often ad nauseam

). This will help you work through the problems. I resisted this at first in my own relationship -- as many men do -- but once I started to open up and discuss things, I saw an immediate improvement in our relationship, including how she regards my knife hobby, which she was (and still probably is) very unhappy about.
3- Use separate bank accounts and manage your money independently of each other. This way you each have the freedom to spend any money you earn that is left over after the household expenses and life savings (very important) are taken care of.
4- Spend less time on your knife hobby and more with your wife. It will make both of you happier in the long run.
5- Live within your means. Don't buy knives (or anything other than a car, house or other large item) on credit. After a year of controlling your spending, you will see your savings start to mount and will be able to buy everything (short of those major purchases) with cash. This is very liberating and removes a lot of stress from the relationship.