You would have to dig into the non-canon language to find a good translation since the canon is missing words like "fang", "tooth", or "claw". Here we'll use the word "Iisk", for "fang". There are a couple ways you could say it:

• "Alduinro iisk": literally, "Alduin's fang"
• "Iisk do Alduin": "the fang of Alduin"
• "Iisksealduin": "the fang of Alduin", but made into a compound word.

Take a look at page 13 of this guide for more on the rules of possession!