Kantian gloves

“It is as if one were to say “The king in chess is the piece that one can check.”. But this can mean no more than that in our game of chess we only check the king.” – Wittgenstein, Philosophical Investigations, §136
What is the ‘but’ for here? What sort of subtle distinction is Wittgenstein making here? He is showing that a remark about what seems like a property of a thing can be translated into (or can mean no more than) a remark about what we do with a thing.

If we generalize this insight, we get: There is a Kantian projection-into-the-thing, but the projection does not stem from the subject, from our cognition, but from our actions, from our dealings with the thing. (We are not wearing Kantian glasses, but rather something like Kantian gloves.)