There are two goals to your question:
First, to keep you valuable knives secure. Second, to keep the in good condition.
For security, nothing beats a bank deposit box.
Failing that, you need a real security safe in your house. Keep in mind that there is a huge difference between a security safe and a fire-resistant container. Fire resistant containers are intended primarily to protect paper business records from fire. Some fire-resistant containers resemble safes and are secure enough to keep out children and spouses taking inventory. But, they are certainly not security safes. Most are, if nothing else, light enough to be picked up and simply taken away intact to be opened at a "more convenient" location. Use the search feature here at bladeforums.com to uncover several past threads on safes.
Also, search on "insurance" to read some good discussions about insurance coverage for collections.
Keeping your knives in good condition is another matter altogether. I prefer to store mine in Bill's Custom cases (you can get 'em from bladeart.com among other places). Bill's cases are the best I've seen. Be very wary of cases with foam interiors. Foams can slowly release chemicals that can coat your knives (you've seen this same sort of film buildup thing on the inside of the windows of your car). Also, foams can break down chemically over time. Finally, foams can trap moisture near your knives. Beware of storage pouches made of plastic materials. Plastics always contain chemicals that can migrate out over time and plastics also trap moisture. Beware of leather. Leathers are also made with dyes and chemicals that can migrate out over time. And beware of cloth, especially velvet and felt. These can also contain dyes that can, over time, stain your knives. (I was once shown a wonderful knife with genuine ivory inserts. It was in perfect condition until you turned it over and saw that the ivory on the other side was stained pink. The owner had left it for years sitting in a display case lined with red felt. The dye from the felt had stained the ivory. Ruined. What a pitty.) Bill has carefully selected the materials that line his cases to avoid all of these problems.
The best way to protect collectible knives from rust and the environment is to use the same product used by virtually every major museum in the world including the British Museum, the Metropolitan Museum of Art, the Museum of Modern Art, and the White House, Renaissance Wax. Do a search here on bf.c and also a general web search and get yourself some.