The verse states: “Moreover I (Jacob) have given to you (Joseph) one portion above your brothers, which I took out of the hand of the Amorite with my sword and with my bow” (Genesis 48:22) ... What is the meaning of “with my sword”? This refers to prayer. What is the meaning of “with my bow”? This is referring to requests. (Babylonian Talmud, Bava Batra 123a)
Jacob assures Joseph that he will be given as an extra inheritance land that Jacob conquered with instruments of war. The Talmud, however, reinterprets these words from weapons to prayer. Presumably, Jacob used both. Similarly, when preparing for a confrontation with his brother Esau, Jacob prepares for war, by dividing his camp into two, and prays to God. The lesson is obvious. Humans must do whatever they can to prepare for and fight incoming danger. However, they must also realize that all is in God's hands and turn to Him in prayer.
Two of the Pevensie children receive opposing gifts from Father Christmas - but they oppose in different contexts. Peter receives a sword and shield. The sword is an offensive weapon while the shield is a tool of defense. They are opposites in the context of war. Lucy receives a dagger and a healing cordial. The dagger is to cause harm while the cordial is to remove harm. Again, the gifts are opposite but now in the greater context of human welfare.
Then there is Susan. She receives a bow (and arrows) and a horn. The bow is to actively fight, as is Peter's sword and Lucy's dagger. What is the purpose of the horn? Well, a priori a horn could be used to arouse the troops to war. But that's explicitly not the purpose of Susan's horn. Father Christmas says, that blowing the horn will bring assistance. But presumably it is not just some regular help one would receive from a typical call. No, it must be divine help. In other words, Susan's horn is an instrument of prayer. And, like the other two, her gifts are opposites, but now the context is how to contend with the physical world. Does one work, try, and persevere, or lay back and let God take care of it?
Susan's horn also reminds us of the ram's horn (shofar) blown every Jewish New Year (Rosh HaShana). The function of the shofar is multifaceted. Rambam states that the shofar arouses people, not to war, but to repentance. But the shofar may also function as prayer - a prayer with no words, a prayer in which we ask God to fill in what we need, because we do not actually no.
And perhaps that is the function of Susan's horn - a vehicle of prayer without words. Therefore, Father Christmas cannot know what type of help will be received. No one can know - not even the petitioner (the one who blows the horn) can know because that is exactly the point. God Himself will fill in the blanks and send the assistance He knows is appropriate.
This may also explain why the horn should not be blown without forethought. Of course, prayer can and should be recited every day, not only in our darkest hour. But that doesn't mean the shofar should be blown every day. Both are powerful tools but retain their power over us due to their uniqueness.
As we have seen, the context of Susan's gifts is more global, perhaps even more theologically fundamental then the other gifts. Presumably this was not arbitrarily done, for it is Susan who grapples most with the natural versus the spiritual.
I think we need to look at Susan's fate one more time...
