The ornamental design for a weightliftinggrip, as shown and described.
FIG. 1 is a top, front, left perspective view of a weightlifting grip showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines immediately adjacent to the shaded area define the bounds of the claimed design and form no part thereof. The broken lines depicting the remainder of the weightlifting grip show features that form no part of the claimed design.