Handmade knives require more care than a standard shop bought knife. Most of my knives are made with carbon steels which are 'reactive'; this means the blades will develop a patina over time and will change the appearance of the blade surface over time. The patina is natural oxidisation on the surface of the blade. It's not harmful, this is simply the story of its use on the surface of the blade. Patina formation helps prevent rust, but occassionally if the blade is left wet or covered in acidic foods rust will begin to form quite quickly. A little rust is nothing to worry about and can be removed by gently scrubbing with the coarse side of a dish sponge.
The knives have to be handwashed and dried after use. They cannot be put in a dishwasher- ever. This will destory the wooden handle and can damage the blade. Looking after your knife is easy once you get in the habit of wiping it after use and occassionally oiling it.
Most of the blades are ground very thin for cutting performance and can chip if used to chop brittle foods like bones.
No knife stays sharp forever. How often you need to sharpen your knife will depend on how often you use it. I recommend getting a double sided whetstone and using that to sharpen your knives. There are many great video tutorials online explaining the process.