When I try to sculpt with dyntopo on a sword it creates really weird results while it works just fine on other meshes. Any idea what causes this?
I made a quick test and it might be also that your object has other scale than 1,1,1.
The solution is to have your object selected and in the object mode press Ctrl+A and select Scale from the Apply menu.
Here I have more than 15 for the Z scale of a cube and the dyntopo sculpt result with the same settings as yours is quite stretched, like yours.
After applying the scale to 1,1,1, dyntopo behaves way nicer, again with the same dyntopo settings as yours:
We might need more info here.
If you are using a texture, make sure your brush size and dyntopo settings make that you create enough geometry in order to make the texture's details correctly.
Also, check the strength of the stroke, too much strength with a texture is rarely good.
Otherwise, that might be an issue from your original mesh's geometry.