Calling you veteran gamers

I used to play this game at University but never finished it, which always bugged me.

When I eventually managed to kill the 2 bosses (big bears/trolls or something) with the spear it told me that my weapon had no magic power and showed me a picture of the shield. It then sent me back to the bottom of the Castle

I don't see how I could kill them with the shield as it had no range, does anyone know how you got to complete the game?