The ornamental design for a hard platevest, as shown and described.
FIG. 1 is a perspective view of a hard plate vest.
FIG. 2 is a front view of a hard plate vest.
FIG. 3 is a back view of a hard plate vest.
FIG. 4 is a right side view of a hard plate vest.
FIG. 5 is a left side view of a hard plate vest.
FIG. 6 is a top view of a hard plate vest.
FIG. 7 is a bottom view of a hard plate vest; and,
FIG. 8 is a perspective view of a hard plate vest showing items attached to the hard plate vest, broken lines are for illustrative purposes only and form no part of the claimed design.