The ornamental design for a robotic armendeffector, as shown and described.
FIG. 1 is a front, top and right and perspective view of a robotic arm end effector showing a second embodiment of our new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The dash-dash broken lines shown in the drawings depict portions of the robotic arm end effector do not form part of the claimed design. The dash-dot-dash broken lines in the drawings depict the boundaries of the claimed design and form no part thereof.