What's the best metal to use for making a sword?

I have my doubts. I always carry a knife, and since I keep losing them, I keep buying them. Long ago, the kind of knives I buy were all regular steel. However, they became trendy, corrosion darkens the blade, and people don’t want blackened blades. So, they began to produce them using stainless steel, which is worthless for a blade (it can’t keep an edge). From then on, I was sold several different stainless steel alloys that, according to the sellers, were as good as standard steel. They weren’t. None of them. Not by a long shot.

I can’t tell for sure that this particular stainless alloy isn’t equal or better to basic carbon steel. But I don’t buy it. Maybe it’s the best stainless alloy available, but the best steel alloy? It will take a lot of evidences to convince me of it.
(FTR, I’ve now my knives custom made, again with regular steel blades)