I received a wooden butter knife in the mail fairly recently: now my only question is this, will it need sanding to maintain its food worthiness or does it require something else to keep it food safe? I got it from Amazon.com if it helps. 
It's hard to say exactly without knowing what wood it's made out of and how it was constructed - there are many factors to the durability of wooden tools and utensils. If all you are using this for is spreading butter, margarine and the like then you shouldn't need to do too much care, just wash it and especially dry it thoroughly after use. It's rotting that is usually the issue with wooden utensils. I wouldn't sand it unless bits of wood start sticking out of it, which could happen depending on the direction of the grain. Sanding without having a good reason could actually cause you more problems then it would solve as you'll be rubbing off any finish it came with. 