The ornamental design for a handguard, as shown and described.
FIG. 1 is a perspective view of the disclosed hand guard;
FIG. 2 is a front view of the disclosed hand guard;
FIG. 3 is a right side view of the disclosed hand guard;
FIG. 4 is a top view of the disclosed hand guard;
FIG. 5 is a bottom view of the disclosed hand guard; and,
FIG. 6 is a perspective view during use of the disclosed hand guard.
The broken line showing a human hand holding the hand guard is for environmental purposes to show use of the disclosed hand guard and forms no part of the claimed design.