In the middle of the fort is an NPC known as the Short Man, who will play a riddle game with you. There are 4 riddles total. If you answer all of them correctly, you will receive the Elf's Helm, Elf's Langseax, and Elf's Shield.
After answering one of the riddles correctly you will lose 5,000 peningas, as the Short Man says the question was "too easy". This is unavoidable, but well worth the cost for the items.