Tying up a couple of loose ends that have been bothering me 
While you are waiting on your armor and sharpened weapons, the castle magic-user sends a message:
"Greetings! I wish you well in your future adventures! I just wanted to inform you that my research has discovered that my 'double' was a doppleganger and you did well in driving it away from the castle, as it could have conceivably taken over the castle eventually unless it was caught. And it had the nerve to impersonate me! Thanks and good luck!"
When you return to the blacksmith for your gear, he holds out the mace from the adventure that Si'Nat had sold him, saying, "Here, I can't keep this in good faith. I always run a Detect Magic on any items sold me and this came up as magical. The castle magic-user identified it as a Mace +2. Since you saved Haven, I will 'sell' it back to you for 250 gp - it's really just the replacement costs of the Detect Magic and Identifying it."
While you are waiting on your armor and sharpened weapons, the castle magic-user sends a message:
"Greetings! I wish you well in your future adventures! I just wanted to inform you that my research has discovered that my 'double' was a doppleganger and you did well in driving it away from the castle, as it could have conceivably taken over the castle eventually unless it was caught. And it had the nerve to impersonate me! Thanks and good luck!"
When you return to the blacksmith for your gear, he holds out the mace from the adventure that Si'Nat had sold him, saying, "Here, I can't keep this in good faith. I always run a Detect Magic on any items sold me and this came up as magical. The castle magic-user identified it as a Mace +2. Since you saved Haven, I will 'sell' it back to you for 250 gp - it's really just the replacement costs of the Detect Magic and Identifying it."