And here I see a problem with your story already. You say your character is closely associated with his dagger, but you can't describe the dagger itself. Once you nail down that little detail, it should be easy enough to find an appropriate blade or even have  someone make it for you.

What makes the blade so special and distinctlive that it brings this character to mind?

 

As for Clothing, I know that DAZ has several medieval style outfits, but  the ones I know of are for M3 and M4. I haven't really kept up with anything for Genesis.