The word "unsure" describes someone who is uncertain, or someone who lacks confidence when performing a particular action. On the other hand, the word "destiny" refers to one's future or fortune, usually with the implication of being something unavoidable.
A sentence that employs these words could be:
"Although the knight was unsure about which path to take, he did no doubt that he would eventually get to the princess, as marrying her was his destiny."