If you collect knives and/or swords as a hobby, you will want to know how to care for your special collection. The best possible source for these answers, might be found with someone who does this sort of job for a living, such as a person working in a museum, maybe in the historical artifacts area.
The first thing they suggest to care for your knife and sword collection, is to keep your hands and fingers off of the blade, as much as possible. The oils in your fingers will affect the steel and metal in your knives. When you can, use cloth (preferably cotton), gloves to handle your collection. If the blade does get touched accidentally, wipe it down as quickly as possible with a white cotton cloth.
Another handy bit of advise, is to keep your knives and swords away from direct sunlight. The rays from the sun can fade your handles. It also affects any leather and other materials that your knives may be incased in. If you want to display your collection in a display case, move it away from direct sunlight that might be coming thru the windows. Using silica gel or window tinting of a light shade, will help protect them from direct light also.
Try to keep your collection in a moderately controlled temperature. You will also want to make sure they are not subject to great deals of humidity and moisture from the air. Try not to store your piece's in the attic, where temps get much hotter then the rooms of your house downstairs. Also avoid the garage, where the temperature fluctuates too much. If you don't display them in a case, the best probably place for them is inside one of your closets, that children don't have access to, of course. It's not a bad idea to store each individual knife or sword in a container like a box.
If you have rust on one of the knives or swords, you can lightly rub a cotton cloth dipped in a bit of kerosene over the spot. Never use an abrasive cloth or substance on your blades, or you may damage them permanently. You should apply an oil made for knife surfaces after you clean the rust spots off.
Don't try to sharpen the blade of an antique. It will not only reduce the value of the piece, but may ruin it, if it is so old that it can't hold up to aggressive sharpening methods.
You need to oil your blades at least once a month. Doing this provides protection against rust and general wear and tear. Some of the oils suggested for using on your blades, are camellia and clove oil. There are blade oils that you can buy too, which should work just fine. They also offer a wax you can use, for after you have oiled your blade. It's called Crystalline wax, and is available at most supply stores.
Any time that you hold your knife or sword, do so by the handle. If you are holding someone else's, it is impolite to run your fingers up and down the blade, besides being a good way to cut your fingers!
If your sword and knife collection is valuable, or holds special sentiment, you may consider getting it insured. To do this, you will need to take pictures of each individual piece, it's sheath if it has one, the display case, and any materials you use for the collection.
Most importantly, unless you are experienced in the art of sharpening your blades, never attempt to do it yourself. It's worth the extra money to have a professional do the job.