Need to find a movie

I need help to find a movie:

The film starts with a story about a prince born in a castle and receives a magical sword , or perhaps a stick , here I am in doubt. Prince's father dies , or gets lost somehow. form of red magic shield , maybe a curse around the entire castle. When the prince gets older he will go out and look for his father or maybe just explore , I can not remember it . But he go through the shield and will quite quickly come across by what I remember a giant frog/monster. The boy kills the frog after it has tried to fool the sword or stick from him and he continues his journey. He meets a nice girl / princess . in the end I believe contains a fight with a dragon that has taken up residence at the palace roof and want to keep the castle for themselves. The effects I remember as mediocre , much like the Labyrinth , but definitely worth seeing.