sketxz,
In your case, you may use two paths and have it look right, one being the horizontal shaft, the other being the arrowhead made from two segments, the end point of the former coinciding with the midpoint of the latter.
If you create the shaft and the upper part of the arrowhead as one path, you will get the unwanted bit sticking out, unless you change to Roud Caps/Joins, which is clearly not what you want.