The characters of the Witch and Aslan are completely opposite. Aslan is kind to his people and the Witch is cruel and demanding towards them. Aslan’s servants desire to serve him because he is a good ruler; just like a child wants to please their father when he is good to them. The Witch’s servants obey her for fear of their lives and their family’s lives! She gets what she wants by forcing her subjects to get it for her, and Aslan’s subjects merely do it out of respect for him or perhaps as an act of attempting to repay him. I say attempting because Aslan resembles God and we are His subjects; God may work a miracle in our life and we try to repay Him by say surrendering something to Him, though we never truly can repay anything that God has done for us. It is the same scenario with Aslan and his subjects.
Aslan has been ever since the beginning of Narnia when the Emperor cast the spell on Narnia and inserted the ‘Deep Magic.’ The Queen has been for quite some time as well, but not since the beginning.
Aslan brings spring because it is warm and comforting, just like him. The Witch brings winter; cold, bitter, fierce storms, icy, deadly, yet beautiful and tempting are the Witch’s winters as well as her demeanor. Aslan not only demands respect, but respect from his subjects towards others; he tries to teach them to posses the qualities he does. He is also a neat and clean being as expressed by making it clear to Peter that he must always clean his sword. The Witch demands respect toward her, but obviously sets a horrid example to her subjects which is why most of them are ugly, filthy, people and creatures, some involved in witchcraft.

From what I got out of the scenario, I think that Peter winning his spurs is an expression meaning that he needed to experience what it feels like to be face to face with an enemy seeking his death and force yourself to spring up and kill for the safety of your people; in this case his own sister. With this possibility in mind, he had to prove himself worthy that he was willing to kill for those that he loved no matter what his mind was telling him against killing. He had to prove that the love in his heart firing up his means of protection was stronger than fear and that he could withstand the bloody battle ahead. Over time he will come to love the Narnians and be happy to risk his life on their behalf.