Knives are rarely sold by the NPCs, since the NPCs seem to use them for themselves. This means for example that swords are easier to obtain by trading than knives which seems to be a little strange. I can easily find a battlesword but it seems almost impossible to find any small knives. As knives are needed for many daily tasks there should be a need of knives in the game world in such a way that the knives are more common than swords. Thus, I suggest to slightly increase the amount of knives in the game.
It might be also a nice idea to make different cultures offering different knives in the way they need them the most (small knives for carving, broad knives for skinning and so on).