Lucy now noticed something lying lengthwise on the table which had escaped her attention before. It was a knife of stone, sharp as steel, a cruel-looking, ancient looking thing.
(The Voyage of the Dawn Treader)
Aslan's Table has not just food as a reward for those who have come so far, but also a knife of stone, not to touched, and later revealed to the very knife that the White Witch used to kill Aslan. It is found there to be kept in honor while the world lasts.
That the tool of Aslan's death should be honored by Narnia should not be surprising from the Christian perspective. After all the tool of Jesus' death, the cross of his crucifixion, is perhaps the most prominent of all Christian symbols. What is surprising is that it is brought to this island and not kept in honor in Narnia or elsewhere. It is so remote that we hear of this knife only when used by the White Witch and in the Voyage of the Dawn Treader. Why is it on Aslan's Table?
Perhaps there are a couple of possible approaches to this. The first is that the knife was placed there as a test. The heroic art of Navigation should be, like the study of the bible and the giving of charity, a means of cleansing the soul. A way of improving the character of those who engage in its depths. But what if it is not? What if the study of Navigation was performed simply for material gain, like on the island of Deathwater rather than as a means of exploring God's world and uplifting humanity?
Then, upon reaching the island, one may take the knife and use it upon his fellows. How could one of noble character strike out his fellow shipmates and adventurers? Only if his quests were motivated by ignobility. That is what happened to the three lords, and as punishment they were cursed to navigate no more.
A second approach may be that the Knife is on Aslan's Table as a reminder. That sometimes, sacrifice will accompany or even be a requisite to ultimate victory. Aslan was about to achieve all he hoped for in Narnia. The White Witch was to be defeated. Human rulers were to ascend the throne of Narnia once more. The Winter had turned into Spring and Narnia was ready to fulfill the mission Aslan had set for it from the very beginning. But at that moment, Aslan had to sacrifice himself. So too with our enterprising navigator. He has been victorious! He has reached the beginning of the end of the world There is nothing beyond but calm seas and smooth sailing. Even here, at the home base, there is everything to meet one's physical desires. But even at this moment of triumph, our navigator must remember the sacrifices that went into his quest. Perhaps it was the sacrifice of children left behind without a father, of a lover forced to say goodbye, of a community left without their leader. Remember their sacrifice and your own and make the choice of where to go next.