Tell me more about these daggers. What effects were on them? Or where they on the AH already disjuncted? My latest (albeit old now) theory was that if random loot had keen on it already, that it would cause the failure when cannith crafting keen on the disjuncted. But who knows. The more info you have about the daggers you started with, the better! What min level, what effects present, slots, etc.
If we can pool our resources and don't mind losing our, uh, resources, maybe we can finally find a pattern to this madness. So grab some random loot, take a screenshot before anything, and try to reproduce! (the bug