if you think a knife with a 5 inch blade can't be considered a weapon just because it folds, you are badly mistaken.
I think you can consider anything you want a weapon, but it all comes down to the intended purpose of the item.
Usually pocket knives are supposed to be used for utility, not stabbing. I'm sure you can find an example of a folding warblade, but I can also find a cane with a sword inside, that doesn't mean all canes, or even most canes, are weapons.