When Richard administered the "Which of these things belong to you already" test to young Locke in 'Cabin Fever,' Locke's selection of the knife struck a chord a fear in Richard; his reaction to the choice was one of terror, not surprise. Had Locke selected the Book of Laws, Richard's mind would have been at ease, as Locke would be in line with Jacob, willing to follow him and his orders. But Locke's selection of the knife implies that Locke is a potential loose canon, a rogue - a man who might try to overthrow Jacob for power, using his knife, his weapon of choice, to "...kill him," as stated in 'Follow the Leader.'
Richard's reaction foreshadowed what is happening presently on the Island - Locke's potential seizing of power by way of the knife, ignoring rules and hierarchy (Book of Laws), and leading his people to the Temple "So [he] can kill him."
Richard's reaction foreshadowed what is happening presently on the Island - Locke's potential seizing of power by way of the knife, ignoring rules and hierarchy (Book of Laws), and leading his people to the Temple "So [he] can kill him."