That sounds like a voice from reductionist’s camp. Are you saying that knowledge is not a virtue or that virtue is something serious people shouldn’t be talking about (because they so understand that ‘All virtues are simply mental models that approximate human social behaviors’)?
Why is it necessary to construct knowledge as a virtue, and why should other concepts priviledged as 'virtues' be intimately related to or derived from it?
To begin with, I think you've definitely chosen the wrong word - surely 'understanding' would be a more useful starting point?
I admit that your intention is an attractive proposition in an intellectualised worldview, but it seems like a somewhat arbitrary approach. A general, fundamental 'moral virtue' emphasising 'fairness' emerges from the dialectical view of morality, and I suppose this could be related to the pursuit and valuing of understanding/knowledge. You would need to work on your idea of 'virtue' in general and 'all other virtues' specifically to explore this further...
Knowledge is a very serious topic and I’ll post here some thoughts on this later on. Is it a virtue or not? Hm, that actually is the core of the question. Knowledge is something that has to be defined. Do people who believe in god have the knowledge of it? Can it actually be called knowledge? My opinion is that this is not a knowledge. It is rather believe.
But ask anybody from the church crowd and they will furiously argue that they do know for sure. Modest ones will say that they have strong faith in what god is. Clever ones will say that we can’t prove that there is no god (and they will be absolutely correct because the god is worse even than then dark matter – he doesn’t even bent gravitation so he is absolutely undetectable and therefore knowledge isn’t able to estimate any of his properties).
But they have something in hand – scriptures. For me it is something like a manual for an alien coming to our planet and knowing absolutely zero what do here and how to behave with people. So if he wouldn’t read scriptures careful enough it will not occur to him that one shouldn’t steal, kill, commit adultery etc.
OK, fine, we have a good book. Could this book be seen as basis for the knowledge about god? Yes it could if all that it contains are facts. Are they? Well, here we come at the watershed. There are still some people who claim that scriptures are all truth. I think we can leave them aside because it probably wouldn’t be possible to discuss anything with them. But there is a number of people who would agree that those texts are too old and naïve but they will still cling to them because of some wise quotations.
This last group is particularly interesting in relation to our discussion because it looks like they confirm that there are no real facts about god but nevertheless there is something that is so nice about him that they simply can’t afford to abandon their believes.
Well, what that might be? I guess these are all those commandments and other good advises and examples from the scriptures that are promoting decent living. In other words virtues.
So we finally arrived to this virtues stuff. But imagine that alien is not so dumb. What if he is clever enough to understand that killing is a bad thing to do? I think most of us understand it very well. I‘m personally absolutely convinced that no child is born killer or thief. We have good enough brain to understand that some things must not be done without any scriptures. Just as self preservation. And this understanding is IMHO based on knowledge of certain things and this knowledge by itself cam make us full of virtues.