How would you trace this spear head.

Dilly Dally,

For preservation of the shape with a regular stroke, you can trace the middle of the strokes using a narrow(er) stroke in a contrasting colour and no fill and with Round Join (to give the roundings at the corners, I always set Round Cap to go with it even when unnecessary as here), with View>Smart Guides being your friends for snapping, and easier with rotation as shown by Doug:

1) For the outer spearhead shape (behind the inner shape which hides the middle of the rounding), with the Pen Tool ClickDrag from the lower right corner and a Handle length about one third of the way, then ClickDrag from the lower left corner and without letting go hold the Alt/Option key and Drag back into the Anchor Point (to make a corner, Smart Guides say origin when you are within snapping distance), then Click the tip Anchor Point, then Click the first Anchor Point to close the path (Smart Guides say anchor);

2) For the shaft, simply create a rectangle with the right width and place it, extending up behind the inner spearhead shape (which hides the top);

3) For the inner spearhead shape in front of the others, with the Pen Tool simply Click the tip and the two lower corners;

4) Adjust as needed with the Direct Selection Tool, moving Anchors and/or Handles;

5) Set the desired Stroke Weight;

6) Fill all the paths, and set the colours as desired.