There are hundreds (thousands) of knives that are missing.
What is the purpose of your collection? Do you simply collect, or do you use them? If you use them, what are your primary uses or requirements?
Your thread would have been better off simply saying "Here's My Knife Collection", rather than asking what is missing. Spend some time reading on this forum and you will see members have posted hundreds of threads about their knives. Then YOU can decide what is missing, based on your requirements and budget.
With no context provided or parameters of your requirements given, this is silly.