Handle suddenly appears when drawing with brush tool

[JackieF]

Why do I suddenly get this dragging handle when I'm drawing with the brush?

 

[MEB]

You have enabled the Stabilizer in the context toolbar (on bottom) for the Brush or Pencil tools. Tap the Stabilizer button and select No stabiliser to turn it off. If you don't see this option tap the small white arrow on the right of the context toolbar to show additional options (including the stabiliser button).

[JackieF]

Thank you!

I was looking for a way to adjust the sensitivity to the pen. not to simplify strokes as much as it do. 

[DM1]

You can adjust pressure sensitivity by selecting the appropriate pen brush and long pressing, then tap edit. You can see the pressure profile, tap it to edit. Alternatively just choose a different pen preset from the menu list.