So as we all know, Hiccup is left handed.

But in dragon training, he always held his weapon in his right.

Viking shields did not have any straps for the arms to slip through, which allowed for the shields to be easily shifted from left to right.
Source

I think this shows that Hiccup would rather protect himself from a feisty dragon than harm one, because as he said himself, he wouldn’t kill a dragon. Make what you will of this though, these are just my observations.