I can see how someone could have more than one grail knife. Think about it. Let's say you have a fixed blade hunting knife and an EDC folder. Two different knives with two different uses. You could have a grail for each one. If the basic definition of a grail is any item that is being earnestly pursued or sought after, you could have many at the same time.
Maybe some of you guys are looking at this with more of a "holy grail knife" attitude. You know, the last knife you will ever buy. It's blade steel is perfect and it only needs to be sharpened once every five years. Even then it is only a minor touch up. The scales are made out of your favorite material and fit your hand (with or without gloves) like the knife was made just for you by the ancient gods of Greece. Fit and finish are second to none. Every other knife you own will be useless because this knife can be used for everything from peeling an apple to batoning redwood trees. In other words, the perfect knife. I hope you find it.
I would love to find a holy grail knife but have come to terms that there is no such beast. My grail knife would be one that I have zero complaints about. With time, I can find something wrong with every knife I pick up. Love the blade steel but hate the scales. Or, the knife fits my hand but the shape of the blade does not meet my needs. Fit and finish are sub standard. Something.
I used to search for grails and I learned much along the way. For me, first and foremost, knife ergonomics come before anything else. Second, the type of blade steel is less important than a good heat treatment. Third, decent fit and finish are a must. With them come a better chance of a safe knife. Fourth, the concept that you can have one knife for ALL your needs is a false one.
Now, I look at knives differently. I look for deal breakers.Things about the knife that I am not willing to overlook. My wallet is now fatter than it used to be and I enjoy the knives I have much more. I can't help but think that you folks have played a role in that. Thanks.