The ornamental design for a weighted discgolftrainingaid, as shown and described.
FIG. 1 is a perspective view.
FIG. 2 is a left side view of the weighted disc golf training aid, the right side is a mirror image of the left side;
FIG. 3 is a top view of the weighted disc golf training aid, the bottom view is a mirror image of the top view;
FIG. 4 is a front view of the weighted disc golf training aid, the bottom view is a mirror image of the top view; and,
FIG. 5 is a front view of the weighted disc golf training aid The broken line showing of the hand and arrow markings are for illustrative purposes only and form no part of the claimed design.