So after reading about this amazing drake sword that could help a noob like me, I decided to see for myself. I've tried many times to shoot off the tail of the dragon but to no avail. I have 12 dex which is enough to use the shortbow from the merchant and I've probably shot about 18 large arrows and he wouldn't give in. I've failed many times because I ran out of arrows and I actually heard he regens health which is why when I came back with more arrows nothing happened. How many arrows should I use and should I be using the large or regular arrows?

I used the cheapest arrows to get it, estimating it took some 30-40 shots with those.

Regular arrows. Bring 30-40 if you're accurate. More if you miss often.

I used the regular cheap ass arrows and it took about 30 of them. I'm not sure if that was the exact number, but that is what I have heard it is. I can tell you for sure that it is easily more than twenty, but I got distracted and lost count when I was doing it. It felt like 30 though.